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Final report Annex 6: Guidance on the notion of ‘major accident’ (Task 6)

Development of an assessment methodology under Article 4 of Directive 2012/18/EU on the control of major-accident hazards involving dangerous substances (070307/2013/655473/ENV.C3)

Report for the European Commission (DG Environment)

AMEC Environment & Infrastructure UK Limited

in association with INERIS and EU-VRi

December 2014

December 2014 Doc Reg No. 34075CA016i6

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Document Revisions

No. Details Date

1 Preliminary version of intermediate report chapter for DG ENV comment

27 March 2014

2 Intermediate report 12 May 2014

3 Intermediate report (revised) 21 July 2014

4 Intermediate report (revised) 11 Sept 2014

5 Draft final report 18 Nov 2014

6 Final report 12 Dec 2014

iv


List of abbreviations

ADAM Accident Damage Assessment Module

ADR European Agreement Concerning The International Carriage Of Dangerous

Goods By Road

ALARP As Low As Reasonably Practicable

ARIA Analysis, Research and Information about Accidents

BLEVE Boiling Liquid Expanding Vapour Explosion

BOD – COD Biochemical Oxygen Demand – Chemical Oxygen Demand

CE Critical Event

CFD Computational Fluid Dynamics

CLP Classification Labelling Packaging

COMAH Control Of Major Accident Hazards

DA Deterministic Approach

ECHA European Chemicals Agency

e-MARS Major Accident Reporting System

EU European Union

EWGLUP European Working Group on Land Use Planning

F&EI Fire & Explosion Index

GHS Globally Harmonised System

JRC Joint Research Centre

LPG Liquefied Petroleum Gas

LUP Land-Use Planning

MAHB Major Accident Hazard Bureau

MATTE Major Accident To The Environment

MF Material Factor of the Dow’s Fire & Explosion Index

MIMAH Methodology for Identification of Major Accident Hazards

NFPA National Fire Protection Agency

NOEC No Observable Adverse Effects Concentration

PA Probabilistic Approach

v


PLG Pressurised Liquefied Gas

RID European Agreement Concerning the International Carriage of Dangerous

Goods by Rail

RMP Risk Management Plan

STOT-SE Specific Target Organ Toxicity (Single Exposure)

USEPA United States Environmental Protection Agency

UVCE Unconfined Vapour Cloud Explosion

Physicochemical parameters

BCF Bioconcentration Factor

EC50 Median Effective Concentration

ΔHr Standard enthalpy of reaction

Kst / Kg Maximum rate of explosion pressure rise for dust clouds/gas

LD50 / LC50 Median Lethal Dose / Median Lethal Concentration

LFL / LEL Lower Flammability Limit / Lower Explosion Limit

LOC Limiting Oxygen Concentration

MIE Minimum Ignition Energy

MTSR Maximum Temperature of the Reaction Synthesis

NOEC No Observed Effect Concentration

Pmax Maximum explosion pressure

Pvap Vapour pressure

ΔTad Adiabatic temperature rise

Teb Boiling point

TMRad Time to maximum rate in adiabatic condition

UFL / UEL Upper Flammability Limit / Upper Explosion Limit

vi


Contents

List of abbreviations iv

1. Introduction 1

1.1 Purpose of the Report 1

1.2 Scope of Task 6 1

1.3 Structure of the Report 2

2. The Definition of ‘Major Accident’ 3

2.1 Overview 3

2.2 Annex VI of the Seveso Directive 3

2.3 Definitions applied by Member States 5

2.3.1 Belgium 5

2.3.2 Czech Republic and Romania 6

2.3.3 Denmark 7

2.3.4 Finland 8

2.3.5 France 8

2.3.6 Greece 8

2.3.7 United Kingdom 8

2.4 Relevance for the assessment methodology 9

3. Threshold Values for Dangerous Effects 11

3.1 Overview 11

3.2 Generalities on threshold values 11

3.3 Defining level of severity 13

3.4 Defining a level of severity in the context of the assessment methodology 16

3.5 Thermal radiation 18

3.6 Overpressure 20

3.7 Toxic Release 22

4. Member States’ Land-use Planning 30

4.1 Overview 30

4.2 Member States’ land-use planning approaches 31

4.2.1 Background 31

vii


4.2.2 Restriction of land use by zoning 32

4.2.3 Restriction of land use based on consequence 39

4.2.4 Restriction of Land use based on the probability of Damage 42

4.3 Other criteria for defining major accidents 54

5. Recommendations on Determining Potential for a Major Accident 55

5.1 Overview 55

5.2 Annex VI of the Seveso Directive 55

5.3 Level of harm 55

5.4 Effects thresholds 56

5.5 Land use planning approaches 57

Table 2.1 Comparison of criteria for defining major accidents in Czech Republic and Romania 6 Table 3.1 Scenario relevance for specific phenomena 12 Table 3.2 Overview of phenomena with quantitative values 12 Table 3.3 Possible severity ranking of effects for human health damages 13 Table 3.4 Correspondence between generic level of harm and level of harm selected by Member States 14 Table 3.5 Reversible and irreversible damages in selected Member States 16 Table 3.6 Overview of level of severity for the assessment methodology 17 Table 3.7 Overview of thresholds for thermal radiation (in kW/m2) 19 Table 3.8 Overview of thresholds for overpressure (in mbar) 21 Table 3.9 Comparison of applicable tools for health effects 26 Table 3.10 Comparison of the toxicity thresholds for selected substances under different methodologies 27 Table 3.11 Overview of thresholds for toxic release 28 Table 4.1 Distances reported for inner zones 33 Table 4.2 Safety distance in Finland 34 Table 4.3 Safety distances for specific buildings in Iceland 35 Table 4.4 Distance for natural gas sites and liquid hydrocarbon gas storage warehouses 36 Table 4.5 Type of land use authorised in zones in Catalonia 37 Table 4.6 Safety distances in Catalonia for specific substances and phenomenon 38 Table 4.7 Appropriate safety distances in Sweden 39 Table 4.8 Sensitivity level of buildings in Cyprus 40 Table 4.9 Land use planning decision matrix for new and existing developments 41 Table 4.10 Type of development and zones in Greek land use planning 42 Table 4.11 Values defined for location based risks 44 Table 4.12 Decision matrix for land use based on individual risk 45 Table 4.13 Scale of gravity depending on the number of people involved. 47 Table 4.14 Range of probability scale 47 Table 4.15 Risk matrix in French assessment 48 Table 4.16 Application of zoning in PPRT 49 Table 4.17 Compatibility table for LUP in Italy 50 Table 4.18 HSE assessment per type of building 53 Table 4.19 Decision matrix for HSE in UK 54 Table 5.1 Example of possible reference distances in the context of Article 4 57

Figure 4.1 Social risk calculation in Flanders, the Netherlands and the UK 43 Figure 4.2 Zones restrictions around Seveso sites 45 Figure 4.3 Zone definition from the PPRT process 49 Figure 4.4 Representation of location risk in the Netherlands 51 Figure 4.5 Representation of societal risk in the Netherlands 52

Appendix A References

1


1. Introduction

1.1 Purpose of the Report

This report forms part of the outputs of a contract for the European Commission on ‘development of an assessment

methodology under Article 4 of Directive 2012/18/EU on the control of major-accident hazards involving

dangerous substances’. The work has been undertaken by AMEC, INERIS and EU-VRi.

The present report concerns one of a number of specific tasks under the project. It should not be read in isolation,

but in conjunction with the main report and the reports concerning the other project tasks.

1.2 Scope of Task 6

The Article 4 assessment methodology explicitly relates to situations where it is impossible for a substance to cause

“a release of matter or energy that could create a major accident”. (The aim of the overall assessment methodology

is to identify the steps to be followed in order to decide whether a substance or a mixture can cause a major

accident (or not). As such, defining what accidents are to be considered as major accidents is an essential part of

the methodology.

The aim of this task was to develop guidance on the limits above which an accident would be considered “major”,

taking into account the fact that a major accident is already defined in Article 3. The terms of reference for this

project defined two main aspects to be explored in order to gain a better understanding of the concept of a major

accident.

Firstly, to take into account the identification/analysis and comparison of national cut-off values

regularly applied in several Member States in the framework of land-use planning policies. The work

therefore involved analysing such national policies and their respective cut-off values applied to the

various scenarios considered (thermal radiation, overpressure, toxic release, etc.). Conclusions have

been drawn on how these cut-off values may guide the interpretation of the notion of a “major

accident” in the context of Article 4.

Secondly to conduct an analysis and comparison of national definitions and guidance on the notion of

“major accident”, and to draw recommendations from this.

Related to the above, the terms of reference for the project indicate that the criteria listed in Annex VI of the

Directive (which aim to identify major accidents that are subject to notification) could constitute a useful starting

point/framework for specifying the notion of major accident. However, it results from the definition in Article 3

that a major accident covers any “serious danger to human health and to the environment”, which goes beyond the

major accidents subject to notification.

These aspects were approached with the objective of understanding whether and how they could be useful in

informing decision making in the context of Article 4.

2


Having undertaken the above analysis, and discussed the findings at a workshop involving experts in the Seveso

directive, it is clear that:

The approaches applied in the context of land use planning for Seveso establishments, and the criteria

used for reporting in Annex VI of the directive are some of the only quantitative measures related to

determining whether a major accident can occur.

However, it is not straightforward or necessarily appropriate to use these approaches to decide on

whether an accident scenario can constitute a major accident. The complexities of how these

approaches are applied, and their limitations, mean that they are probably inappropriate on their own

to form a basis for determining whether a major accident is possible.

Further work is likely to be required before any consensus can be reached on how to determine

whether a major accident is possible based on predictive accident scenarios.

The report includes various material on different methodological approaches, as well as on how the Seveso

Directive is implemented in different member states. This material is only presented in terms of its use in

informing possible assessments under Article 4; it does not reflect any advocacy or criticism of the merits (or

otherwise) of how the Directive is currently being implemented. It is therefore only to be used and understood in

the context of the Article 4 assessment methodology.

1.3 Structure of the Report

This report is structured as follows:

Section 2 presents the information collected on the definition of a major accident;

Section 3 presents a review of some Member States’ legislation in relation to land use planning and

setting safety distances in order to avoid a major accident; and

Section 4 summarises threshold values used in Member States for thermal radiation, overpressure and

toxic release.

3


2. The Definition of ‘Major Accident’

2.1 Overview

Article 3 of the Seveso Directive defines a major accident as ‘an occurrence such as major emission, fire or

explosion resulting from uncontrolled developments in the course of the operation of any establishment covered by

this Directive and leading to serious danger to human health or the environment, immediate or delayed, inside or

outside the establishment, and involving one or more dangerous substances’.

Based on this definition, the Joint Research Centre (2005) highlights three criteria to be fulfilled to qualify an accident

as a “major accident”1:

The accident must be initiated by an “uncontrolled development”;

“One or more dangerous substances” listed in Annex I of the Directive must be involved;

The accident must lead to “serious danger” to human health, the environment or the property.

The two first criteria are viewed as relatively unambiguous, unlike the third one about “serious danger”. As the

assessment methodology is aimed at applying across all Member States, it was important to look at additional

elements that could help understanding how the notion of ‘major accident’ could be defined within the context of

Article 4.

For this, a literature review was undertaken in order to identify other elements that could assist in the application of

the Article 3 definition in the context of the assessment methodology including a review of the extent to which

other elements such as Annex VI or Member States’ definitions/interpretations of ‘major accident’ could be used in

the assessment methodology.

Throughout, it should be borne in mind that the definition in Article 3 is the essential starting point. It covers

accidents with effects outside or inside the establishment.

2.2 Annex VI of the Seveso Directive

Article 18 of the Directive requires that a ‘major accident’ meeting the criteria listed in Annex VI of the Directive

has to be reported by Member States to the Commission. As such Annex VI determines criteria for the mandatory

reporting of a major accident to the European Commission. However, these criteria are not equivalent to a

‘definition’ of what constitutes a major accident. Nonetheless, these criteria may be a useful starting point when

attempting to define a major accident within the context of Article 4. They are:

1 Joint Research Centre, 2005, Guidance on the preparation of a safety report to meet the requirements of Directive 96/82/EC as amended by

Directive 2003/105/EC (Seveso II), Institute for the Protection and Security of the Citizen

4


“1. Any fire or explosion or accidental discharge of a dangerous substance involving a quantity of at least 5% if

the qualifying laid down in Column 3 of Part 1 or in Column 3 of Part 2 of Annex I.

2. Injury to persons and damage to real estate:

A death;

Six persons injured within the establishment and hospitalised for at least 24 hours;

One person outside the establishment hospitalised for at least 24 hours;

Dwelling(s) outside the establishment damaged and unusable as a result of the accident;

The evacuation or confinement of persons for more than 2 hours (persons × hours): the value is at

least 500; and

The interruption of drinking water, electricity, gas or telephone services for more than 2 hours

(persons × hours): the value is at least 1 000.

3. Immediate damage to the environment:

Permanent or long-term damage to terrestrial habitats:

- 0.5 ha or more of a habitat of environmental or conservation importance protected by legislation;

- 10 or more hectares of more widespread habitat, including agricultural land;

Significant or long-term damage to freshwater and marine habitats:

- 10 km or more of river or canal;

- 1 ha or more of a lake or pond;

- 2 ha or more of delta;

- 2 ha or more of a coastline or open sea;

Significant damage to an aquifer or underground water: 1 ha or more.

4. Damage to property:

Damage to property in the establishment: at least EUR 2,000,000;

Damage to property outside the establishment: at least EUR 500,000.

5. Cross-border damage: any major accident directly involving a dangerous substance giving rise to effects outside

the territory of the Member State concerned.

5


2.3 Definitions applied by Member States

Examples of the definition of a major accident applied in several Member States are presented below, note that

these examples are not exhaustive. For a selection of Member States, the following definitions of major accident

have been identified.

2.3.1 Belgium

The Cooperation Agreement2 includes the following definition: an incident such as major emission, fire or

explosion that is the result of uncontrolled developments during the operation of an establishment which falls under

the provisions of this Agreement, and that results in either an immediate or a delayed serious hazard to the health of

persons within or outside the establishment or to the environment and that involves one or several dangerous

substances’.

Further details were identified at federal level.

Federal level

An accident is major if it meets the following criteria3:

The event is the consequence of an uncontrolled development happening during the operation of an

establishment falling under the scope of the Cooperation Agreement. An uncontrolled development is

an anomaly that has developed to such an extent that it is out of control for the operator. In many

cases, it is noted that the speed of the event is a determining for the ‘loss of control’ over the situation;

The event leads to serious danger, either immediate or differed: for individuals inside the Seveso

establishment (employees, sub-contractors or visitors), and /or for individuals outside the Seveso

establishment and or for the environment; and

One or several dangerous substances are involved in the event, the quantity of the substance involved

is not important in the assessment of whether the accident is major.

Some further explanations are provided for serious danger to individuals. These consider either a

bodily injury or health damage4. The effect can be immediate or at a later stage. However chronic

effects due to a long-term exposition to a small concentration of toxic substances are not considered to

be a serious accident.

It is only required that a situation of serious danger ‘appears’ and does not take into account the actual

damages that have arisen from the event. The likely consequences (what could have happened), and

2 Cooperation Agreement Between The Federal Government, The Flemish Region, The Walloon Region And The Brussels

Capital Region Concerning The Control Of Major-Accident Hazards Involving Dangerous Substances, internet link:

http://navigator.emis.vito.be/milnav-consult/consultatie?language=en 3 Service Public Federal, Emploi, Travail et Concertation Social, Accident majeur,

http://www.emploi.belgique.be/defaultTab.aspx?id=6264 4 Service Public Federal, Emploi, Travail et Concertation Sociale, Accident majeur,

http://www.emploi.belgique.be/defaultTab.aspx?id=6264

6


not the actual injury or damages (what has happened) are considered when assessing the seriousness of

an accident.

Finally, it is not necessary that the effects are beyond the Seveso establishment boundaries for it to be

considered a major accident.

2.3.2 Czech Republic and Romania

Responses to the survey indicated that the definition of a major accident adopted in these two Member States is

very similar to Annex VI. The details of the definitions are presented in the table below. The text in bold

highlights variations from the text of the Directive.

Table 2.1 Comparison of criteria for defining major accidents in Czech Republic and Romania

Czech Republic1 Romania2

Major accidents caused by hazardous substance or discharged in an amount equal to or exceeding 5 % of any of the quantities of hazardous substances listed in Annex 1 to this Act by section 1 of Table I or II, column 2

n/a

Fatal accidents caused by dangerous substances listed in Annex 1 to this Act Part 1 leading to the formation of one or more of the following events : a) death , b) injury of at least 6 employees or other individuals residing in the building or facility if their hospital stay exceeded 24 hours , c ) injury to at least one person outside the facility or facilities if the hospital exceeds 24 hours ,

Injuries of the persons:

a) a deceased; b) injury of the 6 persons inside the plant and their hospitalization for at least 24 hours; c) injury of one person outside of the plant and the hospitalization at least for 24 hours;

d) damage to one or more dwellings outside object or device that accidentally became uninhabitable , e) The need for evacuation or sheltering of people in buildings for more than two hours , if the total converted time of evacuation or sheltering persons ( persons multiplied by time ) exceeds 500 hours , f) interruption of the supply of drinking water , electricity and thermal energy , gas or telephone services for more than two hours , if the total time converted interruption (number of people multiplied by time ) exceeded 1000 hours .

Causing damage to the property goods: a) causing damages to one/several buildings outside of the plant and destruction of this/those, inhabitable as a result of the accident; b) evacuation and distressing people for more than two hours (persons x hours), calculated value at least 500; c) interruption of the supply services for drinking water, electricity, gas or telecommunications for more than two hours (persons x hours) in the case where the resulted value by multiplication of the affected persons by the numbers of hours of interruption of the above mentioned services, to be at least 1.000;

7


Czech Republic1 Romania2

Fatal accidents caused by dangerous substances listed in Annex 1 to this Act , Part 1 , if it results in environmental damage on:

a) areas protected by special regulation (..), i.e. especially protected areas and Natura 2000 zones declared water conservation and protection zones sources of mineral water with an area equal to or greater than 0.5 hectares , b ) the other an area equal to or greater than 10 ha , c ) the watercourse length equal to or greater than 10 km , d ) natural or artificial surface water body without the status of water tank under a special law , an area reaching or exceeding 1 ha .

Fatal accidents caused by dangerous substances listed in Annex 1 to this Act, Part 1, if it results in environmental damage collector, i.e. the geological environment in the saturation zone and elsewhere in the site collection or accumulation of groundwater or groundwater pollution with an area equal to or greater than 1 hour.

Causing immediate harmful effects against the environment: a) permanent damages or on long term on terrestrial habitats:

-0.5 ha or more from an ecological valuable habitat or by conservation, protected by law; -10 ha or more from a more extended habitat, including agricultural land;

b) significant damages or on long term on the surface waters habitats or marines (where is the case, in the damage evaluation process can be made references to the legislation regarding the dangerous substances and chemical mixtures or the lethal concentrations for 50% of the species representatives from the affected environment):

-10 km or more from a river or a channel; -1 ha or more from a lake or a pond; -2 ha or more from a Delta; -2 ha or more from a coastal water body or an open sea;

c) significant damages of an aquifer or ground waters (where is the case, in the evaluation process of the damages can be made references to the legislation regarding dangerous chemical substances and mixtures or the lethal concentrations for 50% of the species representatives of the affected environment):

-1 ha or more

Fatal accidents caused by dangerous substances listed in Annex 1 to this Act , Part 1 , if it results in a) damage to property or equipment originator of a major accident in the amount equal to or exceeding CZK 70 million (current exchange is approx. 1 Euro=26 CZK.) b) damage to property outside the building or equipment accident originator of equal or exceeding 7 million CZK.

Causing damages of the properties: a) damages of the properties from the plant, with a value in RON’s represents the equivalent of at least 0.5 million euro; b) damages of some properties outside of the plant perimeter, with a value in RON’s represents the equivalent of at least 0.2 million euro

Fatal accidents caused by dangerous substances listed in Annex 1 to this Act, Part 1, leading to effects outside the territory of the Czech Republic.

Causing transboundary damages: any accident in which is present a dangerous substance and can produce effects outside of the national territory.

Note 1 Czech Republic national legislation (Act No. 59/2006 coll. on the major accidents prevention

Note 2 Romania, Minister Order No.1084, 22/12/2003 on the Notification procedures which represents major accidents production dangers in which are involved dangerous substances and respectively, of the produced major accidents.

Furthermore, in Czech Republic any accident which includes a significant release of dangerous substance; an

explosion or fire is considered to be a major accident5.

2.3.3 Denmark

Major accidents are defined in the Risk Executive Order (Bekendtgørelse om kontrol med risikoen for større uheld

med farlige stoffe Stk. 5). These are “event on a larger scale, such as emission, fire or explosion resulting from

uncontrolled events in connection with the operation of an establishment subject to this Order in which one or more

5 Survey response

8


of the substances mentioned in Annex 1, and, immediately or later may cause significant harm to someone at the

company or outside the company or the environment”6.

2.3.4 Finland

A major accident is an accident that results in permanent injury or prevents people from evacuating their homes or

present location7.

2.3.5 France

A major accident means an occurrence such as a major emission, fire or explosion resulting from uncontrolled

developments in the course of the operation of any establishment covered by the Seveso Directive and leading to

serious danger to human health and/ or the environment, immediate or delayed, outside the establishment, and

involving one or more dangerous substances. Accidents occurring inside the installation are dealt with by the

occupational safety legislation.

2.3.6 Greece

Major accidents can have consequences outside and/or inside an installation. They are not only accidents with

external consequences. In addition, one research article8 argues that an accident can be considered as “major” if it

involves one of the substances included in Annex I of the Seveso Directive in a quantity equal or greater than the

limits provided in that Annex. This interpretation is not easy to implement as an accident does not always involve

the total quantity of the substance present in an establishment.

2.3.7 United Kingdom

Under the COMAH Regulations9, it is considered that a single fatality would be the lower bound cut-off for a major

accident. A guidance document has been published by the Health Safety Executive10 . This document states that

the term ‘major accident’ does not include less serious accidents or other incidents such as authorised discharges of

pollutants as part of the normal operation of plant. Furthermore, an occurrence will be a major accident if it meets

the following conditions:

Results from uncontrolled developments at an establishment to which the Regulations apply; and

Leads to serious danger to people or to the environment, on or off site; and

6 Presentation by Morten R. Østergaard, Danish EPA, Land use planning in the Habour area in the municipality of Aarhus,

DenmarkApplication of a Danish Administration Practice on Land Use Planning, 24 September 2012, Cyprus 7 Niks Jan Dujim, 2009, Acceptance Criteria in Denmark and the EU 8 I.A. Papazoglou, Quantitative Risk Assessment For Accidents At Work In The Chemical Industry And The Seveso II

Directive, System Reliability and Industrial Safety Laboratory 9 Implementing the Seveso Directive in UK national legislation 10 HSE, 2006, A guide to the Control of Major Accident Hazards Regulations 1999 (as amended) (L111)

9


Involves one or more dangerous substances defined in the Regulations, irrespective of the quantity

involved.

Further guidance is included to define uncontrolled development and serious danger to people or to the

environment.

As a separate point, an incident will be a major accident if it results in serious danger to the environment. The

UK’s guidelines for what constitutes a ‘major accident to the environment’ provide substantially more elaboration

than the criteria for reporting in Annex VI of the Seveso Directive. Thresholds are defined for each of a number of

different categories of environment11 and for the extent of damage in the event of an accident, which are used in

order to determine whether such an accident would be considered a MATTE (example of thresholds for level of

harm for marine water are included in the Task 3 report).

2.4 Relevance for the assessment methodology

Article 3(13) of the Seveso III Directive provides for the definion of a major accident. Furthermore, Annex VI has

been drafted in order to identify major accidents that need to be reported by Member States to the European

Commission However, Annex VI is not a list of criteria defining a ‘major accident’ which is confirmed by wording

of the relevant mother Article 18 of the Seveso Directive by referring to ‘major accidents meeting the criteria of

Annex VI’. This suggests that it is possible to have major accidents that do not meet the criteria of Annex VI.

This idea is supported by the fact that the extent of consequences of accidents described in the criteria differ from

the extent of accidents that initiated the negotiation for a Seveso Directive at a European level12. In applying the

criteria listed in Annex VI, a major accident may include some events involving dangerous substances that are

classified as occupational accidents. Pey (2009) underlines that regulations and tools that aim at preventing and

controlling major accidents (e.g. external emergency plans, land use planning) focus the attention on accident

scenarios that cause dangerous effects to people or environment outside an industrial site13. Papazoglou, as well as

Heidebrink (2005) add that, in most Member States, scenarios with effects limited to an area inside the

establishment are regulated under legislation other than Seveso Directive (e.g. ATEX Directive, OSHA regulations)

and handled by different competent authorities (e.g. Ministry of Labour) than those responsible for external

safety14.

As a result, it is important to consider Annex VI criteria only as elements guiding the understanding of the concept

of ‘major accident’ for the purpose of the assessment methodology. Feedback from the participants to the workshop

11 Designated land/water sites (national, international and ‘other’), scarce habitats, widespread habitats, aquifers/groundwater,

soil/sediment, built heritage, particular species, marine and freshwater/estuarine habitats. 12 The preamble to the Seveso III Directive highlights that “major accidents often have serious consequences, as evidenced by

accidents like Seveso, Bhopal, Schweizerhalle, Enschede, Toulouse and Buncefield”. 13 Pey A., Lerena P., Suter G., Campos J, 2009, Main differences on Eurpoean regulations in the frame of the Seveso Directive,

Process Safety and Environment Protection 87 14 Papazoglou I.A., Quantitative risk assessment for accidents at work in the chemical industry and the Seveso II Directive

10


(October 2014) as well as from the project confirmed that the Annex VI cannot be understood as providing a

definition of ‘major accident of themselves.

While some organisations agreed that they could be a useful starting point for deciding whether a major accident is

possible in the context of Article 4 (because they are based on already-agreed definitions), they are not to be

considered “the definition” of a major accident. Other respondents indicated that going beyond the criteria of

Annex VI for defining a ‘major accident’ was not a suitable approach. One respondent highlighted, referring to

Annex VI, that ‘the concept of a major accident has been legally defined within the Directive since 1982 and

reports of significant problems in applying the definition have not arisen’15.

However the review of definitions of ‘major accident’ applied in Member States, showed variation in the

definitions that have been adopted in a number of Member States. As the assessment methodology under Article 4

is to apply horizontally in all EU Member States, any exclusion of substances from the Seveso Directive following

an assessment would need to be agreed with all Member States. It appears unlikely that those Member States with

additional criteria would agree to an exclusion if the substance in question would still be capable to create major

accidents in accordance with their national provisions. Therefore, it appears to be important to consider the most

stringent requirements at least for the initial screening on whether or not a substance is capable of generating a

major accident. Any subsequent detailed assessment could then further investigate the actual risks.

15 Survey response.

11


3. Threshold Values for Dangerous Effects

3.1 Overview

The concept of ‘major accident’ can be defined with reference to its effects and through the comparison of the

national policies and cut-off values that are applied for the following dangerous phenomenon:

Thermal radiation;

Overpressure; and

Toxic release.

3.2 Generalities on threshold values

To assess the consequences of an accident scenario, it is necessary to evaluate the distances by which the

phenomenon’s dangerous effects (i.e. thermal radiation, overpressure and toxic clouds) will give rise to unwanted

effects on human health (e.g. lethality, irreversible damage or reversible damage). The distances can be based on

threshold (or end) values regarding the level of thermal radiation, overpressure or toxic release that may give rise to

the unwanted effects. These values are established on the basis of probit functions that quantify the likelihood of

adverse effects to people at a particular exposure.16

As highlighted in Task 4, the major events (presented in the bow-tie on the fault tree side) are significant effects on

targets (i.e. humans, structures or the environment) from identified dangerous phenomena. The main possible

significant effects in the context of the assessment methodology are the following: thermal radiation, overpressure,

and toxic clouds (affecting humans and the environment).

Table 3.1 summarises the effects that can be assessed for each specific dangerous phenomenon.

16 P.D. Petrolekas and A. Charalambous, Sept 2001, Land use planning considerations in the context of Seveso II Regulations

12


Table 3.1 Scenario relevance for specific phenomena

Dangerous Phenomenon Effects

Thermal Radiation Overpressure Toxic Effects

Fireball X X

Flash fire X

Jet fire X

Pool fire X

Vapour Cloud Explosion X X

Toxic Clouds x

Solids Fire x

Source: Roadmaps for LUP

Table 3.2 describes the possible damage of the effects selected and the chemical property of the substance that

would give rise to the effects.

Table 3.2 Overview of phenomena with quantitative values

Property of the substance Effect measured Possible damages

Flammable Thermal radiation Burn to people, damage to property and the installation

Explosive Overpressure Causalities to people, damage to property and the installation

Toxic Toxic release Intoxication of people


The European Working Group on Land Use Planning (EWGLUP) has worked on the identified differences in LUP

approaches amongst Member States. Guidelines on land use planning were developed by the EWGLUP17.

In addition, the JRC18 has compiled an overview of Roadmaps for Land-Use Planning for selected Member States

which compared Member States’ approaches to complying with Article 12 of the Seveso II Directive. The JRC

selected five Member States for further analysis19 as examples of different methods of fulfilling Article 12

requirements. The JRC refers to the roadmaps as “decisional routes” bridging the gap between risk analysis and

land-use planning. They present the differences in methodologies and practices in Member States. The

17JRC, 2006, Land use Planning Guidelines in the context of Article 12 of the Seveso II Directive 96/82/EC as amended by

Directive 105/2003/EC. This is referred to in the report as ‘Roadmaps for LUP’ 18 JRC, 2008, Overview of Roadmaps for land-use planning in selected Member States 19 The Netherlands, France, Italy, Germany and the UK

13


information presented in the Roadmaps for LUP has been supplemented with information from other pan-European

projects (e.g. ARAMIS20 and ACUTEX21), responses from respondents to the survey for the current project and

additional information on thresholds applied in Member States. These are presented in Sections 3.4, 3.6 and 3.7,

respectively covering thermal radiation, overpressure and toxic release thresholds.

3.3 Defining level of severity

One of the important aspects of the concept of a ‘major accident’ is that it implies a severity which distinguishes it

from other non-major accidents. The assessment methodology needs to define a qualitative level of harm which

corresponds to the concept of major accidents.

The Member States define levels of harm by using concepts such as harmful effects, reversible and irreversible

injuries and lethality. It is important to have a clear understanding of what these mean in order to choose the best

suited corresponding threshold level in undertaking an assessment in the context of Article 4.

There is variation in the level of harm that is taken into account in Member States. In order to compare these

different levels of harms used by Member States, the information gathered for specific Member States has been

classified against a 6-level generic ranking. These generic levels have been defined in accordance with the

information presented in the Roadmaps for LUP and are presented in the table below. A further category has been

created, gathering the various end-values reported for domino effect by Member States.

Table 3.3 Possible severity ranking of effects for human health damages

Level of harm Effects on human targets

Level 1 No effect No injury

Level 2 Small effect Slight injuries without sick leave

Level 3 Reversible injury Injuries leading to hospitalisation

Level 4 Irreversible injury Irreversible injuries or death inside the establishment, reversible injuries outside the establishment

Level 5 Start of lethality Irreversible injuries or death outside the establishment

Level 6 High lethality High number of death inside and outside the establishment

Domino effect

Note: this table is based on information presented in the Roadmaps for LUP (JRC) and information collected on Member States practices

20 ARAMIS, 2004, Accidental risk assessment methodology for industries in the context of the Seveso II Directive, WP2,

Severity evaluation. More information on the ARAMIS project are included in Annex IV (Task 4). 21 In 2006, the ACUTEX project aimed at developing a European methodology for developing Acute Exposure Thresholds

Levels for toxic substance to be applied in major hazard control. As part of the work, the project reviewed the existing levels

or methodologies defined by several countries for toxic substances.

14


The objective of this classification is to be able to directly compare the levels of harm established as thresholds in

Member States but also the associated end-values. However, there are some uncertainties surrounding the exact

definition and boundaries of some of the level of harms in Member States. As a result, these tables are not to be

read as presenting absolute equivalents, but rather a comparison of different approaches adopted in Member States.

The correspondence between the generic level of harm and those identified in Member States only indicative and is

presented in Table 3.4.

Table 3.4 Correspondence between generic level of harm and level of harm selected by Member States

Level 1- no effect

Level 2 - small effect

Level 3 - reversible injury

Level 4 - irreversible injury

Level 5 - start of lethality

Level 6 - high lethality

Domino effect

Belgium

Risk Zone - specific measures to limit the accidents consequences

Belgium (Wallonia)

Zone of surveillance (can affect sensitive persons)

Zone of risk (serious consequences)

Zone of immediate danger (irreversible and lethal consequences)

Zone of immediate danger (irreversible and lethal consequences)

Zone for domino effects

Cyprus

Zone III: a-degree burns in a substantial part of the population

Zone II : c-degree burns to 1% of the population

Zone I c-degree burns at a rate of over 50% of the population

Denmark

Threshold values for maximum consequence distance

Estonia

Very dangerous area

France Irreversible effects

Lethal effects (heavy hazards)

Lethal effects (very heavy hazards)

Greece

Zone III - first irreversible effects

Zone II - first death (1% lethality)

Zone I - multiple fatalities

Zone D - domino effects (severe damage to equipment)

Italy Reversible effect

Irreversible effect

Start of lethality

High of lethality Risk of domino

15


Level 1- no effect





Level 6 - high lethality

Domino effect

Lithuania Reversible injury

Irreversible injury

Beginning lethality High lethality Domino effect

Slovenia Widest impact area

Wider impact area

Inner impact area

Spain Alert Zone (ZA)

Intervention Zone (ZI)

Domino Zone (ZD)

The Netherlands

Where 1% lethality would occur under the most adverse climatological conditions.

UK (in TDU)

50% fatality for offsite planning,

1-5% fatality for LUP

ARAMIS Small or no effect

Reversible effects

Irreversible effects

Start of lethality Domino Effect

Roadmaps for LUP - Non Stationary Radiation No effect Small effects

Reversible effects

Irreversible effects Lethality

Roadmaps for LUP - Stationary Radiation No effect Small effects

Reversible effects

Irreversible effects Lethality

The differences observed between Member States are not a judgement on the levels of safety applied in the member

states or a suggestion that some member states’ approaches are more (or less) protective than others. They are only

used as an illustrative example of the diversity of approaches, and are only applicable in the context of reviewing

possible approaches for the Article 4 assessment methodology. Therefore, the above should not be interpreted as a

statement or an assessment of the implementation of the Seveso Directive in these Member States.

Whilst the level of harm defined as ‘lethality’ or ‘fatality’ is quite clear in that it involves the death of at least one

or several persons, there are more ambiguities in the definition of reversible and irreversible effects.

Some work has recently been published on regulation of industrial risk in the then ‘new’ Member States22. The

report presents for seven Member States the types of damages that are considered to be reversible or irreversible.

Table 3.5 summarises the information reported.

22 JRC, 2007, Risk Mapping of Industrial Hazards in New Member States.

16


Table 3.5 Reversible and irreversible damages in selected Member States

Reversible damage Irreversible damage

Member State

Human Infrastructure Environment Human Infrastructure Environment

Bulgaria Injury

Economic loss

Loss of functionality

Public service interruption

Damage to habitat

Economic loss

Death

Disability

Destruction

Uneconomical recovery

Loss of biodiversity

Czech Republic

Injury

Acute effect

Economic loss

Severe damage


Economic loss


Economic loss


Loss of resource

Death

Canter

Health chronic effect

Destruction Loss of resource


Cyprus Injury

Acute health effect

Economic loss

Severe damage


Economic loss


Economic loss Death

Chronic health effect


-

Estonia Injury Severe damage

Economic loss


- Death Destruction -

Lithuania Injury

Acute health effect

Epidemic

Economic loss

Severe damage


Economic loss


Economic loss


Loss of resource

Death

Cancer


Disability

Destruction


Economic loss


Loss of resource

Poland Injury

Acute health effect

Severe damage - Death Destruction -

Romania Injury

Acute health effect

Epidemic

Economic loss

Severe damage


Economic loss



Death

Cancer


Disability

- Loss of biodiversity

Source: JRC, 2007

3.4 Defining a level of severity in the context of the assessment methodology

For the purpose of the assessment methodology, it is recommended that a four level scale of severity could be used.

Table 3.6 presents the thresholds used in the context of the European ARAMIS project, the use of which is

particularly relevant in the context of Article 4 as the results are already well recognised. The thresholds

considered therein are considered to represent the most stringent thresholds used among Member States.

17


Table 3.6 Overview of level of severity for the assessment methodology

This four level approach follows the approach of Member States, but presents a reduced range (no effects, high

lethality and domino effects are excluded23) and maps onto the level of severity identified in Member States. The

following correspondence applies: an assessment methodology Level 1 – small effect corresponds to Level 2- small

effects of Table 3.4. Similarly, Level 4 in the table above corresponds to the Level 5 – start of lethality as


For the purpose of the assessment methodology, it is important that a qualitative level of harm for a major accident

is set if modelling of accident scenarios is undertaken.

However, it must be highlighted that Level 2 (reversible injuries) is a threshold which could be readily reached for

almost any accident scenario, even for non-dangerous substances. It is also important to take into account the

overlap between Seveso, which covers major accidents (with effects that can be on-site as well as off-site), and the

harm that may occur as a result of industrial accidents which can affect a small number of workers on-site and

which are also covered by other occupational safety and health legislation in the EU. One of the difference

between the issues targeted by Seveso and those addressed by worker protection legislation is the loss of control

and containment that lead to the incident or accident. This loss of control indicates that the potential for a more

serious accident existed and this reflects the motivation behind the Seveso legislation.

For the assessment methodology, it is not considered that the scale of effects can be considered in isolation, but

rather defined in relation to conditions relating to the substance under consideration. For example, the distance at

which the effects threshold (reversible and irreversible injury) is exceeded will be an important factor in

determining whether a particular scenario could lead to a major accident.

23 If the accident has no effect it cannot be a major accident. Moreover any effect over start of lethality is a major accident

(according to the Annex VI criteria) so there is no need to assess worse severity than ‘start of lethality’ in the context of

Article 4.

Level 1 Small effect

Level 2 Reversible injuries

Level 3 Irreversible injuries

Level 4 Start of lethality

Thresholds for overpressure effects (in mbar)

ARAMIS <30 30 - 50 50 - 140 >140

Thresholds for thermal radiation (in kW/m²)

ARAMIS - 60 sec <1.8 1.8 - 3 3 - 5 >5

Thresholds for toxic effects

ARAMIS TEEL1-1 – TEEL-2 TEEL-2 – TEEL-3 >TEEL-3

18


3.5 Thermal radiation

Thermal radiation is one of the possible effects from hazardous phenomena. It is generated by the (more or less

rapid) combustion of a flammable or combustible substance.

Table 3.7 presents the threshold values identified during the review of Member States’ practices. The thresholds

values correspond to the levels of harms presented in Table 3.4 and have been assigned to each generic level of

harm according to the definition presented in Table 3.3.

19


Table 3.7 Overview of thresholds for thermal radiation (in kW/m2)

Level 1- no effect





Level 6 – high lethality

Domino effect

Belgium 2.5 (during 30 sec)

Belgium (Wallonia) 6.4 10 10 8, 32 or 44

Cyprus

3 (Zone III)

6 (Zone II) 15

Denmark 6

Estonia 20 (static), 35 (impulse)

France - human 3 5 8

France - structures 3 5 8 16 20 and 200

Greece * 170 450 1,500

Italy 3 5 7 12.5 12.5

Lithuania 3 5 7 12.5 37.5

Slovenia 1.8 - 3 3-5 > or =5

Spain * 3 5

12 for unprotected equipment, 37 for protected equipment

The Netherlands

12.5 ( 20 sec) or 9.8

UK * 1,800

ARAMIS - 30 sec <3 3-5 5-9 >9 >9

ARAMIS - 60 sec <1.8 1.8 - 3 3-5 >5 >5

Roadmaps for LUP - Non Stationary Radiation - <125 125 - <200 200-350 >350 -

Roadmaps for LUP - Stationary Radiation 1.6 <3 - <5 <3- <5 5 - 7 >7

* in TDU – thermal dose unit

Respondents from the Czech Republic and Portugal indicated that no threshold values have been defined in their

Member States. The 2008 work conducted by the JRC on Roadmaps for LUP in selected Member States concluded

20


that overall the ‘divergence of accepted thresholds is not wide’ in the Member States reviewed and it proposed a

default set of values that is presented in the last rows of the table24. The Roadmaps for LUP document makes the

distinction between stationary and non-stationary radiation, however our research found information related mainly

to stationary radiation (which is also most relevant for Seveso establishments).

The table shows that similar thresholds are being relied upon by Member States. It also shows that the most

stringent thresholds are applied in Italy and France with reversible effects starting from 3 kW/m2 and lethality at 7

kW/m2 (for Italy).

In addition, it is interesting to note that few Member States have adopted thresholds for smaller levels of harm (i.e.

Level 2).

If the assessment methodology takes the approach of the most stringent Member State, then Italian values for Level

3 (i.e. reversible effects) should be retained (3 kW/m2). Again, it is not sufficient to consider these types of cut-off

values in isolation in determining whether the potential for a major accident hazard exists. For example, one

person working in a laboratory could be exposed to thermal radiation above such a level, and incur only minor

reversible effects, where the level of harm may be more commensurate with accidents intended to be regulated by

occupational safety legislation. However, if accidents are severe, affect multiple people or the public outside the

site boundary, this is more likely to be classifiable as a major accident.

3.6 Overpressure

Overpressure is the result of a pressure wave. The wave can arise from an explosion, a chemical reaction, a violent

combustion, or a brutal compression or decompression of pressurised gas (e.g. the burst of a bottle of compressed

air).

Table 3.8 presents the threshold values that have been identified during the review of Member States practices.

The thresholds values correspond to the levels of harm presented in Table 3.4 and have been assigned to each

generic level of harm accordingly.

24 JRC, 2008, Overview of Roadmaps for land-use planning in selected Member States

21


Table 3.8 Overview of thresholds for overpressure (in mbar)

Level 1- no effect






Domino effect

Belgium 20

Belgium (Wallonia) 25 50 160

Cyprus 50 140 350

Denmark 50

Estonia 200

France - human 20 50 140 200

France structures 20 50 140 200 200/ 300

Greece 50 140 350

Italy 30 70 140 300 300

Lithuania 30 50 120 530 1,000

Slovenia 20-50 50-140 > or =140

Spain 50 125

160 for atmospheric equipment, 350 for pressurised equipment, 100 for building

The Netherlands 100

ARAMIS <30 30 - 50 50 - 140 >140 >140

Roadmaps for LUP <30 30 - 50 50 - 140 >140

The values reported by France and Italy appear to be the most stringent of those identified. The table shows that

the thresholds values reported by Member States are quite similar, and that both ARAMIS and the JRC report on

Roadmaps for LUP have adopted an identical range of values to use as default values.

In the context of the assessment methodology, the lower range of the values proposed by the ARAMIS project as

default values matches the values of the most stringent Member State and those proposed in the JRC report on

Roadmaps for LUP. These values could be used as the threshold for identifying a major accident due to

overpressure in the context of Article 4. So for example, if Level 3 was to be considered as the relevant level of

harm, the overpressure limit for the purpose of the assessment methodology would be between 30 and 50 mbar.

22


3.7 Toxic Release

Toxic release effects result from the absorption of a hazardous toxic substance (or preparation) due to a leak on an

installation, the release of a toxic substance from chemical decomposition during a fire or a chemical reaction.

The JRC report on Roadmaps for LUP found that it was difficult to compare the methods chosen by Member States

to assess the effects from toxic release for the following reasons25:

Countries only agree one threshold, which is the level corresponding to the start of certain effects (for

example irreversible health effects).

There are several existing exposure guidelines and it is not straightforward to choose one rather than

another. In addition there is little data available on effects on humans. Most data is from animal

experimentation extrapolated to humans.

Each of the guidelines and level-setting methodologies cover only a limited number of substances, and

several need to be combined when they sometimes recommend different values.

The effects of the toxic substances can be linked to the dose rather than the concentration. In these

cases, the dose can depend on the concentration value, the exposure time but also others parameters.

The effects will vary according to the person affected, their age and their health conditions.

Threshold levels and Methodologies

There are several existing methodologies that Member States have reported using for assessing toxic effects. The

main ones are described below26.

Acute Exposure Guidelines Levels (AEGL)

This methodology has been developed by the US National Advisory Committee on AEGLs under the US EPA27.

Three levels are defined with exposure times of 10 minutes, 30 minutes, 1 hour, 4 hours and 8 hours:

AEGL-1: the airborne concentration (in ppm) of a substance above which it is predicted that the

general population, including susceptible individuals, could experience notable discomfort, irritation,

or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient

and reversible upon cessation of exposure.


general population, including susceptible individuals, could experience irreversible or other serious,

long-lasting adverse health effects or an impaired ability to escape.

25 JRC, 2008, Overview of Roadmaps for land-use planning in selected member States 26 JRC, 2008, Overview of Roadmaps for land-use planning in selected member States 27 American Environmental Protection Agency, Acute Exposure Guidelines Levels,

http://www.epa.gov/oppt/aegl/pubs/define.htm

23



general population, including susceptible individuals, could experience life-threatening health effects

or death.

Dangerous Toxic Load (DTL)

These load levels have been developed by the UK Health and Safety Executive28.

Specified level of toxicity (SLOT): The airborne concentration level at which almost everyone in the

exposed area is likely to suffer severe distress, a substantial fraction of which will require medical

attention, and some people will be seriously injured, requiring prolonged treatment. For highly

susceptible people, the possibility exists that they will be killed.

Significant likelihood of death (SLOD): The airborne concentration level at which the mortality of

50% of an exposed population is predicted.

Emergency Exposure Indices

The indices have been developed in 1991 by the European Centre for Ecotoxicology and Toxicology of

Chemicals29. Apart from two exemplary chemicals, no further values have been developed. Exposure times are 15,

30 and 60 minutes. Three levels are defined:

EEI-1: The maximum airborne concentration below which the exposed population is not likely to

suffer discomfort.

EEI-2: The maximum airborne concentration below which the exposed population is not likely to

suffer irritation.

EEI-3: The airborne concentration below which the exposed population is not likely to be

incapacitated.

Emergency Response Planning Guidelines (ERPG)

These guidelines have been issued by the American Industrial Hygiene Association30. Three levels are defined

with an exposure time of 1 hour:

ERPG-1: The maximum airborne concentration below which it is believed nearly all individuals could

be exposed for up to 1 hour without experiencing more than mild, transient adverse health effects or

without perceiving a clearly defined objectionable odour.


be exposed for up to 1 hour without experiencing or developing irreversible or other serious health

effects or symptoms that could impair an individual’s ability to take protective action.

28 Health and Safety Executive, Toxicity levels of chemicals, http://www.hse.gov.uk/chemicals/haztox.htm 29 European Centre for Ecotoxicology and Toxicology of Chemicals , http://www.ecetoc.org/index.php 30 American Industrial Hygiene Association, ERPG Guidelines, 2013 https://www.aiha.org/get-

involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPGIntroText.pdf

24



be exposed for up to 1 hour without experiencing or developing life-threatening health effects.

Immediately dangerous to life and health (IDLH)

This threshold has been developed by the American National Institute for Occupational Safety and Health and it

represents the maximum concentration in the air of a toxic substance in which a person can be exposed for 30

minutes without any irreversible damages for his/ her health or injuries which can prevent him/her from leaving the

area31.

Intervention guidelines

These guidelines have been issued by the Dutch Competent Authorities in 1999. Three levels for a 1 hour exposure

are defined32.

Life threatening value (LBW): the concentration of a substance above which death or a life threatening

condition may develop within a few days after an exposure of one hour.

Alarming threshold (AGW): the concentration of a substance above which irreversible or other serious

health impairment may occur as a result of acute toxic effects after an exposure of one hour.

Communication guideline value (VRW): the concentration of a substance at which with a high level of

probability will be perceived by the majority of the exposed population as hindrance or above which

minor, quickly reversible health effects may occur after an exposure of one hour. Often this is the

concentration at which exposed people start to complain about the perceived exposure.

Lethal concentration and dose

A series of statistical data have been calculated which set median lethal concentration and median lethal dose33.

LC50 (Median Lethal Concentration 50): is a statistically derived single concentration of a substance

that can be expected to cause death in 50% of animals when administered by the inhalation route

during 4 hours. The LC50 value is expressed in terms of ppm or mg/m3.

LC1 (Median Lethal Concentration 1): The concentration in the air of a toxic substance, which may

cause fatalities to the 1% of the population via inhalation of the substance for duration of 30 minutes.

LD50 (Median Lethal Dose): is a statistically derived single dose of a substance that can be expected to

cause death in 50% of animals when administered by the oral or dermal route. The LD50 value is

expressed in terms of weight of test substance per unit weight of test animal (mg/kg).

31National Institute for Occupational Safety and Health, pages on IDLH, http://www.cdc.gov/niosh/idlh/default.html 32 ACUTEX, Methodology to develop AETLs, January 2006 33 Regulation (EC) No 1272/2008 on the classification, labelling and packaging of substances and mixtures (CLP Regulation)

25


SEL and SEI

These thresholds have been developed by the French Ministry of the Environment, for exposure times of 1, 10, 20,

30 and 60 minutes and 2, 4, and 8 hours34.

SEL (Lethal Effects Threshold): concentration for a given exposure period above which mortality can

be observed in the exposed population.

SEI (Irreversible Effects Threshold): concentration for a given exposure period above which

irreversible effects may appear in the exposed population.

SER (Reversible Effects Threshold): concentration for a given exposure period above which reversible

effects may appear in the exposed population.

SP (Perception Threshold): concentration that leads to a sensorial detection of the chemical substance

by the exposed population.

Temporary emergency exposure levels (TEEL)

These levels have been developed by the US Department of Energy and are used in the ARAMIS project for setting

default toxic release thresholds35. Four levels have been defined for a 15 and 60 minutes exposure time, depending

on type of chemicals.

TEEL-0: the threshold concentration below which most people will experience no appreciable risk of

health effects.

TEEL-1: the maximum concentration in air below which it is believed nearly all individuals could be

exposed without experiencing other than mild transient adverse health effects or perceiving a clearly

defined objectionable odour.


exposed without experiencing or developing irreversible or other serious health effects or symptoms

that could impair their ability to take protective action.


exposed without experiencing or developing life-threatening health effects.

Comparison of threshold levels

Two comparisons of these toxicity threshold levels, relevant for the assessment methodology, have been identified.

In 2006, the ACUTEX project aimed at developing a European methodology for developing Acute Exposure

Thresholds Levels (AETLs) for toxic substance to be applied in major hazard control36. As part of the work, the

project reviewed the existing systems of acute exposure values in order to understand the range of definitions and

34 INERIS, Portail Substances Chimiques, Seuils de toxicite, http://www.ineris.fr/substances/fr/page/23 35 Advanced Technologies and Laboratories International , Protective action criteria,

http://www.atlintl.com/DOE/teels/teel/teel_pdf.html 36 ACUTEX, Methodology to develop AETLs, January 2006

26


parameters in current use and to identify the difference between them. The results of the comparison are

reproduced in Table 3.9. This provides helpful guidance on the link between the different existing tools available

and how they can be used to assess a heath effect. It is noticeable that the same tool can be used for health effects

with different levels of harm. For example, EEI-3 is used to assess both irreversible and lethal effects (i.e.

permanent incapacity and lethality).

Table 3.9 Comparison of applicable tools for health effects

Health effect Duration of exposure

1 min

10 min 15 min

20 min

30 min 1 hr 4 hrs 8 hrs Probit

No appreciable risk of health effects, not likely to suffer discomfort

EEI-1

TEEL-0

EEI-1

Objectionable odour TEEL-1

EPRG-1

VRW

Mild effects, discomfort, irritation AEGL-1 EEI-1

TEEL-1

AEGL-1

EEI-1

AEGL-1

EEI-1

EPRG-1

VRW

AEGL-1

AEGL-1

Likely to suffer severe distress SLOT

Medical attention required EEI-2 EEI-2 EEI-2 SLOT

Impairment of an individual’s ability to take protective action or escape

AEGL-2 TEEL-2 EEI-2

AEGL-2

EEI-2

AEGL-2

EPRG-2

EEI-2

AGW

AEGL-2

AEGL-2

Serous health effects, serious injury requiring prolonged treatment

AEGL-2

TEEL-2 EEI-2

AEGL-2

EEI-2

AEGL-2

EPRG-2

EEI-2

AGW

AEGL-2

AEGL-2

SLOT

Immediate or delayed permanent adverse health effects, irreversible health effects

SEI SEI

AEGL-2

TEEL-2

SEI SEI

AEGL-2

SEI

AEGL-2

EPRG-2

AGW

AEGL-2

AEGL-2

Permanent incapacity EEI-3 EEI-3 EEI-3

Life-threatening effects AEGL-3 TEEL-3

AEGL-3 AEGL-3

EPRG-3

LBW

AEGL-3

AEGL-3

Likely to cause death, lethal effects SEL SEL

EEI-3

SEL SEL

EEI-3

SEL

EEI-3

LBW

SLOD

Reproduced from ACUTEX, 2006

27


The aim of the ACUTEX project was to define AETLs linked with the existing tools and guidance to measure toxic

effects. For example, for the ACUTEX threshold level 2 (irreversible but not fatal effects), the report found that

there are differences in the effects assessed in different tools: EEI focuses on the prevention of effects leading to

disability while ERPG and AEG focus on the prevention of irreversible and long lasting health effects and

impairment of the ability to escape37.

In addition, the report on Roadmaps for LUP includes a comparison for a selection of chemicals of the results

obtained with IDLH, ERPG and AEGLs. The result of the comparison is presented in Table 3.10.

Table 3.10 Comparison of the toxicity thresholds for selected substances under different methodologies

Substance Thresholds for toxic substances (ppm)

IDLH (30 mins) ERPG3 (1 hr) AEGL-3(1hr)

Ammonia 300 1000 1100

Bromine 3 5 8.5

Chlorine 10 20 20

Hydrogen Chloride 50 100 100

Hydrogen Fluoride 30 50 44

Formaldehyde 20 25 56

Phenol 250 200 Not recommended

Phosgene 2 1 0.75

Sulphur Dioxide 100 15 30

Hydrogen Sulphide 100 100 50

Source: JRC, Roadmaps for LUP

Comparison of thresholds applied in Member States

Table 3.11 presents the thresholds applied by Member States in relation to toxic release. The thresholds values

correspond to the levels of harm presented in Table 3.4 and have been assigned to each generic level of harm

according to the definition presented in Table 3.3.

37 ACUTEX, Methodology to develop AETLs, January 2006.

28


Table 3.11 Overview of thresholds for toxic release

Level 1- no effect






Domino effect

Belgium IDLH

Cyprus IDLH LC1 LC50

Denmark AEGL-3

Estonia IDLH

France SEI SEL 1% SEL 5%

Italy IDLH LC50 LC50

Slovenia ERPG-1 – ERPG-2

ERPG-2 – ERPG-3 ERPG-3

Spain

AEGL 1 –ERPG 1 – TEEL 1

AEGL 2 – ERPG 2 – TEEL 2

The Netherlands D01

UK D50

ARAMIS < TEEL-1 TEEL-1 – TEEL-2

TEEL-2 – TEEL-3 >TEEL-3 >TEEL-3

The table illustrates the diversity of methods used by Member States.

One possible option with regard to the assessment methodology would be to identify the health effects that

constitute the start of a major accident, and using the equivalent level presented in Table 3.9, to ensure that the

substance considered in the assessment methodology does not meet any of the possible thresholds of the tools

available. For example, if it was considered that ‘medical attention required’ is a characteristic of a major accident,

then according to Table 3.9 the assessment must demonstrate that the associated toxicity thresholds (i.e. EEI-2)

cannot be exceeded.

However, it is important to take into account the exposure time as a major accident does not necessarily manifest

effects immediately. The ACUTEX report notes that there are variations in the existing approaches. For example,

the French system uses a time span from 1 to 480 minutes (8 hours). ACUTEX notes that the use of the 480 minute

time span can be problematic as it can be confused with occupational exposure limit (OEL) values that typically

use this time frame38. Finally, the report notes that, in industrial accidents, the release of chemicals would not

typically last more than several minutes, but that in the case of fire, the release of toxic gases can last for days or

weeks.

38 ACUTEX, Methodology to develop AETLs, January 2006

29


In the context of the assessment methodology it is appropriate that the assessment demonstrates that the toxicity

thresholds chosen cannot be exceeded under the various exposure times, which may be up to 8 hours if approaches

amongst the different member states are taken into account. Again factors such as the potential to cause off-site

effects for the public (rather than toxic effects on a small number of individuals on-site may need to be taken into

account).

Whilst the focus of this section has been on acute toxicity, it is important to highlight that the Seveso Directive lists

some named carcinogenic and mutagenic substances in Annex I part 2. For carcinogenic and mutagenic substances

that might be considered in the context of Article 4, endpoint values for such health effects should also be

considered in the context of the assessment methodology, and this can be done in a similar manner to e.g. acute

toxicity. However, given the complexities with e.g. dose-response relationships and threshold levels for effects for

CMR substances, no particular threshold values for comparison are presented here. Such assessments should be

done on a case-by-case basis.

30


4. Member States’ Land-use Planning

4.1 Overview

Article 13 of the Seveso Directive requires that ‘the objectives of preventing major accidents and limiting the

consequences of such accidents for human health and the environment are taken into account in [...] land-use

policies’.

The approaches adopted by Member States and their Competent Authorities with regard to land-use planning are a

potentially important source of information on the interpretation of the dangerousness of Seveso establishments and

their potential to create major accidents. One of the aims of this Task was to consider national cut-off values

regularly applied in several Member States in the framework of land-use planning policies, and to conclude how

these cut-off values might guide the interpretation of the notion of a “major accident” in the context of Article 4.

The Competent Authorities assess the evaluation of hazard and the analysis of risks created by an establishment

before granting planning permission for new establishments or for developments in the vicinity of existing sites.

The potential for the establishment to create a major accident is an important part of this assessment. For this

assessment, the thresholds values defined by Member States for thermal radiation, overpressure and toxicity effects

are used.

A review of Member States land-use policies was conducted. The information reviewed includes Member States’

reporting under the Seveso Directive, Competent Authorities guidelines, recent pan-European projects on chemical

and industrial risks, and other source of information identified during the literature review. A full list of the

information reviewed is included in Appendix A.

Whilst in some member states, the land use planning approaches are effectively used as a surrogate for what is

considered a major accident, this is not universally true. The links between safety distances and cut-off values used

in land-use planning and the definition of major accident is not clear-cut and there is no direct correlation between

the two. However in the context of the Article 4 assessment methodology, these cut-off values and reference

distances represent some of the only quantitative values available to allow for comparison with estimated effects

distances predicted for relevant accident scenarios.

As has become clear during the course of the project, there are a number of practical and theoretical limitations to

the use of these cut-off values and reference distances in deciding whether a major accident is possible in the

context of Article 4. A key consideration is that safety distances for land use planning are often set by taking into

account local conditions and characteristics such as geographical, social, economic and administrative factors.

These local, site-specific factors are not relevant in the context of the Article 4 assessment methodology.

Since these values show how member states consider the suitability or otherwise of developments near to

establishments where a major accident is possible, and because they include quantitative estimates of distances and

relevant cut-off values for dangerous effects, they may be of help to assessors in the context of Article 4. However,

it is clear that they are not suitable on their own for determining whether a major accident is possible, and so this

31


information should be considered as one of a number of elements to take into account when deciding whether

distances to relevant effects calculated for a particular accident scenario constitute a major accident or not.

4.2 Member States’ land-use planning approaches

4.2.1 Background

The European Commission’s land-use planning guidelines describe the most common methods used to assess the

hazard presented by an establishment within land-use planning policies39. They are as follows:

Deterministic approach (also known as consequence-based): The deterministic approach involves

carrying out an assessment of consequences of credible accidents, without taking into account the

likelihood of these accidents. This is in order to avoid uncertainties related to the quantification of the

frequencies of occurrence of the potential accidents40. Under this approach, a scenario is pre-selected

(i.e. a reference scenario), and based on this the modelling of consequences is conducted. The

reference scenario is defined based on expert judgement and historical data and is specific for each

type of establishment. The authorities may require that several reference scenarios are assessed. This

approach involves the definition of effect endpoints (e.g. a tolerability or effect threshold). The

consequences of the accidents are taken into account by calculating the distance at which, for a given

exposure period, the threshold value corresponding to the beginning of the undesired effect is reached.

Using these endpoints, two zones are defined. The inner zone focuses on the immediate boundaries of

the installation and the outer zone is used to separate the installation from densely populated areas or

buildings with sensitive populations.

Probabilistic approach (risk-based): Under this approach, the consequences of potential accidents are

assessed and the likelihood of each scenario occurring is also assessed (thus differing from the

deterministic approach). This method typically consists of five steps:

- Identification of hazards;

- Estimation of the probability of occurrence of the potential accidents;

- Estimation of the extent of consequences of the accidents and their probability;

- Integration into overall risk indices that may include both individual and societal risk; and

- Comparison of the calculated risk with the acceptance criteria.

Under this approach, two types of risk can be calculated: individual risk and societal risk. The risks

defined can be split into categories: typically acceptable, non-acceptable and a region where the risk

can be considered as acceptable but reduction is desired (i.e. ALARP or ALARA). See Figure 4.1 for

a visualisation of these levels.

39 JRC, 2006, Land-Use planning Guidelines in the context of Article 12 of the Seveso II Directive 96/82/EC 40 Institute for Systems Informatics and Safety, 1999, Guidance on Land Use Planning as required by Council Directive

96/82/EC (Seveso II)

32


State-of-the-Art approach: This approach is based on the idea that sufficient measures must exist to

protect the population from an accident considered to be the ‘worst conceivable’. The aim is to

operate without imposing any ‘conceivable’ risk to the population outside the establishment by relying

on state of the art technology and additional safety measures. For land use planning, this approach is

translated in the use of zoning, where zones are derived from the consequences of representative

scenarios.

Hybrid approaches (i.e. semi-quantitative approach): The semi-quantitative approach is a sort of

deterministic approach which includes some quantitative (i.e. likelihood) elements. Some elements

are assessed in a quantitative way, while others are assessed qualitatively. See the description for

France below as an example of a hybrid approach in land use planning.

The review of Member States practices on restricting land use in the vicinity of Seveso establishments has

identified two main trends in zoning policies:

1. The restriction of land use by zoning policies based on the type of establishment, surrounding

infrastructures and/or the type of substances involved; and

2. The restriction of land uses by zoning policies based on vulnerability levels.

The latter can be split into two further groups, one defining zones by reference to consequence levels (deterministic

approach) and the other where zones are defined with reference to probability of damage (probabilistic approach).

4.2.2 Restriction of land use by zoning

This practice is based on the principle that uses of land that are not compatible with each other should be separated

by specific distances. Tables have been elaborated that classify the industries into categories and for each a

specific distance is proposed. Some finer categories can be defined and distances specified in accordance with the

substance used in the installation. This approach has been observed in several Member States and Iceland. Table

4.1 presents a summary of the distances identified. These are not directly comparable as they are set with reference

to different variables. For example, in Latvia and Finland, the distances issued are substance and site specific, for

example for natural gas production and storage sites.

The table summarises the distances identified in several Member States for inner zones. It shows that there is a lot

of variation in zoning practices of Member States and that it may be difficult to choose one minimum distance

rather than another without further information.

33


Table 4.1 Distances reported for inner zones

Estonia Finland Iceland Latvia Spain (Catalonia)

Sweden

No details on the specific zone

Zone established are up to 200 metres

Substance and building specific

5m

10m

25m

350m

130m

55m

Building specific

1,100 m

330m

For natural gas sites and storage installations

450m

300m

150 m

100m

75m

50m

10-50m

Specific to type of establishment

500m

250m

100m

50m

Specific to type of establishment

200m

500m

1,000m

1,500m

The details of the land use practices in relation to zoning for these countries are set out below.

Estonia

Estonia implements the requirements of the Seveso Directive through their Chemical Act and Planning Act. Local

government has to consult with the Rescue Board which assesses a major accident’s probability for the

establishment and their consequences, and gives recommendations for safe planning. The recommendations are

based on the risk and the methodology developed by the Rescue Board that defines zones and the types of

development that can be accepted in each of these zones.

The assessment is deterministic (i.e. consequence based). The Estonian legislation defines several safety zones

according to specific purposes such as environment protection (e.g. coastal protection), health protection (e.g.

radiation, vibration and noise) or for specific type of establishment (e.g. pressure vessel, gas installation or safety

zone for electrical). The zones established contain distances of up to 200 metres41.

Finland

In Finland, minimum distances are provided as a function of the substance and the tank or storage size. The

distances are calculated for the site boundary but also for residential areas and other areas of public use42. The

values used in Finland are presented in the table below.

41 Presentation by Priit Laaniste, Seveso II and land-use planning in Estonia, Estonian Ministry of the Interior, November 2007 42 Institute for Systems Informatics and Safety, 1999, Guidance on Land Use Planning as required by Council Directive


34


Table 4.2 Safety distance in Finland

Substance Tank / Storage size

Separation to public roads or site boundary (in metres)

Separation to residential areas, areas of public use or natural sensitivity (in metres)

LPG 5 t 5 15-25

5-50 t 10 35-50

50-200 t 25 50-100

>200 t Safety analysis Safety analysis

Ammonium nitrate 1-5 t 66 100

5-10 t 100 150

10-15 t 133 200

15-30 t 166 250

30-50 t 200 300

50-100 t 233 350

>100 t 266 400

Ammonia >10 t - 400-600

Hydrogen >120 kg - 150

Unstable gases or flammable liquids

5,000 m3 350 -

Other flammable gases or liquids (process unit)

5,000 m3 130 -

Flammable liquids (tanks) 200 m3 55 80

Source: Institute for Systems Informatics and Safety, Guidance on land use planning, 1999

Iceland

In Iceland, safety distances have been established for top-tier establishments. The distances are presented in the

table below.

35


Table 4.3 Safety distances for specific buildings in Iceland

Type of building Distance

Hospitals, day-care, large assembly rooms and streets with dense traffic 1,100 metres

Residential areas 1,100 metres

Busy roads and harbours 330 metres

Other buildings and public roads 330 metres

Source: Niks Jan Dujim, Acceptance Criteria in Denmark and the EU

In addition, safety distances have been adopted in the legislation for sites dealing with explosives43. This is not

specific to Seveso sites; however, this can be relevant as explosives are covered by the Seveso Directive.

Latvia

The law on Protective Zones sets out special requirements to restrict the development of residential areas and other

activities in the planning territory in the vicinity of dangerous establishments, as well as restricting dangerous

activities in the vicinity of vulnerable areas.

There is a minimum protective zone of 100m around the buildings of pumping and filling stations for oil and oil

products and other dangerous chemical substances and products, reservoir parks, filling and discharge overpasses,

berths and jetties, heating points, warehouses, storage vessels, and processing and reloading enterprises, where oil,

oil products, dangerous chemical substances or products are kept.

The maximum width of the safety protective zone around pipes, tanks and storage vessels used for oil, oil products,

dangerous chemical substances and products, as well as processing and reloading enterprises is 500m.

In accordance with the law on Protective Zones, the following protective zones must be observed around natural

gas sites and liquid hydrocarbon gas storage warehouses, filling stations and other facilities:

43 Survey response

36


Table 4.4 Distance for natural gas sites and liquid hydrocarbon gas storage warehouses

Site Distance of protective zones

Natural gas compressor stations 450m from the external wall of the building or compressor station equipment

Natural gas collection points 300m

Natural gas collector bore-holes located in the natural gas storage area and connected to the collector layer

300m from the bore-hole

Liquid hydrocarbon gas storage warehouses, storage vessels and filling stations

100m

Around gas pipes 75-150 m

Other natural gas and liquid hydrocarbon gas sites 10-50 m


In these protective zones the following activities are prohibited:

The construction of new residential buildings or reconstruction of existing buildings as residential

buildings;

The construction of new sports, educational and recreational buildings and establishments, or the

reconstruction of existing buildings as sports, educational and recreational buildings or establishments;

The construction of playing fields and recreational areas, as well as the organisation of public events;

The siting of petrol filling stations; and

Other operations (or activities) that may interfere with environmental and public safety during the

operation of gas pipes and natural gas and liquid hydrocarbon sites.

Spain

The land use planning system in Spain is based on the definition of three consequences based zones which are

described as follows:

The intervention zone (ZI), the area where immediate protection is justified due to the damage level

caused by the effects of a certain accident.

The alert zone (ZA), the area where immediate protection is not justified (except for critical groups of

the population) due to the damage level caused by the effects of a certain accident. Population within

this area may however perceive the effects of the accident.

The domino zone (ZD), the area where severe damage to property (process and storage equipment) is

expected due to the effects of a certain accident.

In Spain, there is no zone distance set and the basis for defining the limits of the zones are consequences based.

37


Catalonia

The regional legislation defines safety zones where land use is regulated. The aim is to ensure that the inhabitants

within these zones can take protective action in case of an accident44. The area affected by the establishment is

known as the no self-protection zone. Inside this zone the ability of the population to take protective measures is

not guaranteed. Its shape and size are fixed by distance to the source of the risk and the severity of possible

accident.

Beyond the ‘no self protection zone’, two further areas are defined by the Catalonian legislation:

The extreme outdoors intensity zone, inside which the negative consequence for people who are

outdoors and other vulnerable elements could be very severe; and

The general sheltering zone which is characterised by land use constraints, preventive measures and

compensatory actions in order to ensure that the population can be warned and can take self-protection

actions.

This set of three zones is known as the assurance of self-protection zone. Land use is controlled within the zones

and specific uses are prohibited in the no self protection zone. These are summarised in Table 4.5.

Table 4.5 Type of land use authorised in zones in Catalonia

Type of uses No self protection zone Extreme outdoors intensity zone General sheltering zone < No self protection zone > No self protection zone

Transport infrastructure

Yes Yes Yes Yes

Industrial Yes (with risk reduction measures)

Yes (with risk reduction measures)

Yes Yes

Services No No Yes (no shopping centres, and limit of 250 persons per buildings)

Yes

Housing No (except for completion urban areas with growth limited by 5% or 500 people)

No (except for completion urban areas with growth limited by 5% or 500 people)

No (except for completion urban areas with growth limited by 5% or 500 people)

Yes

Other uses No No Yes (e.g. park with low density and maximum 500 people attendance)

Yes

Source: Generalitat de Catalunya Departament d’Interior, Relacions Institucionals i Participació, November 2009

44 Generalitat de Catalunya Departament d’Interior, Relacions Institucionals i Participació Direcció General de Protecció Civil

Subdirecció General de Programes en Protecció Civil, November 2009, Land use and spatial planning: criteria for risk

management

38


The legislation specifies a generic value for the limit of the ‘no self-protection’ zone which can be revised taking

into account specific information about the dangerous substances used in the installation. The preliminary zone has

a default size of 500 metres. Following the in-depth review of the installation’s characteristics, type of storage and

processes involved, the Competent Authority calculate the extent of potential major accidents and decide whether

the zone perimeter needs to be adjusted. It can either be kept at 500 metres or reduced as follows:

500 metres: Catalonia explained that with a wind speed of 1.5 m/s a toxic cloud can reach a distance of

500 metres in 5.5 minutes. It added that it is generally accepted by risk management experts that at

least 5.5 minutes go by, since the instant when the accidental emission begins, before the affected

population can be warned. This is caused by the uncertainty associated with the first moments of the

emergency and is regarded as unavoidable, even with the best warning techniques. This distance is

also used for establishments whose main function is storage and distribution in large quantities of

flammable gases and liquids obtained from oil distillation.

250 metres: This distance is used for flammable liquefied gases and flammable gases if the storage

area does not qualify as large. It also applies to toxic substances which cannot generate large toxic

clouds because their toxicity level is medium or low, their boiling point is high or because it is

prevented by safety arrangements.

100 metres: This distance is used for flammable or very flammable substances that cannot generate

flammable clouds or deflagrate.

50 metres is used for the remaining cases.

Spain allows for physical barriers to be taken into account and reduces the safety distances from 500m to 250m,

from 250m to 100m and from 100m to 50m. The barriers must resist specific constraints and ensure that beyond

them, specific conditions are met. These are summarised in Table 4.6.

Table 4.6 Safety distances in Catalonia for specific substances and phenomenon

Substance type Dangerous phenomenon

Perimeter of the no self protection zone (in metres)

No preventive actions

With preventive actions

Preventive action

Toxic gases and liquids with low boiling point

Toxic cloud 500 350 Chemical detectors

Extremely flammable liquefied gases

BLEVE 500 250 Physical barriers against thermal radiation and shock wave

Very flammable liquid fuels in large distribution centres

Fires, explosions 500 250 Physical barriers against thermal radiation and shock wave

Very flammable liquids (low boiling point)

Flammable cloud, explosion, jet fire

250 100 Physical barriers against thermal radiation and shock wave

Flammable liquids Pool fire 100 50 Physical barriers against thermal radiation and shock wave

Other Spills causing pollution 50 50 -

Source: Generalitat de Catalunya Departament d’Interior, Relacions Institucionals i Participació, November 2009

39


Sweden

In Sweden, the safety distances are provided for 32 different activities. The table below presents some of these

distances. The Swedish legislation considers that these distances are initial values, that can be deviated from

following detailed assessment45. The assessment must take into account reasonable scenarios such as discharges,

fire, smoke from fires, etc.

Table 4.7 Appropriate safety distances in Sweden

Type of infrastructure Distance

Plastic industry 200 m

Paper mill 500 m

Non-organic chemical industry 1,000 m

Oil refinery 1,500 m

Industrial block 50 m

Small industry area 200 m

Industrial area 500 m

Process industry >1,000 m

Source: Guidance on land use planning, 1999

4.2.3 Restriction of land use based on consequence

In the following Member States, zones that restrict land uses are defined by reference to specific effect and

thresholds (as presented in Section 3). For example zone I is the zone where a specific effect would affect a

defined number of people (e.g. 50% if the population affected by c-degree burns in Cyprus, or would reach a

specific threshold 1,200 ppm of toxic release in the Czech Republic). This represents the application of the

consequence based (deterministic) approach for which reference scenarios are assessed. Reference scenarios are

defined by the authorities and the establishment operator. Using the defined threshold values for thermal radiation,

overpressure and toxic release, zones are defined surrounding the establishment.

Cyprus

In Cyprus, the land use planning advisory system takes into account the consequences of major accidents, the type

of developments and the level of sensitivity of the buildings surrounding an establishment.

45 Institute for Systems Informatics and Safety, 1999, Guidance on Land Use Planning as required by Council Directive


40


Three consequence based zones are defined for land use planning purposes46. The distances of the zones are not

defined but are derived from the consequences of major accidents in agreement with specific endpoints for thermal

radiation, overpressure and toxic cloud:

Zone I is the inner zone where c-degree burns would affect over 50% of the population, severe and

irreparable damage to the supporting structure and walls of buildings or a toxic cloud would cause

death of 50% of the population.

Zone II is the zone where c-degree burns would affect 1% of the population, damage to the supporting

structure and exterior or interior walls of the establishment or a toxic cloud would cause death of 1%

of the population.

Zone III is the zone where a-degree burns would affect a substantial part of the population, damage to

doors and windows, light cracks in the walls and a toxic cloud would create imminent danger to life.

A generic sensitivity level is set for each type of infrastructure, as presented in Table 4.8.

Table 4.8 Sensitivity level of buildings in Cyprus

Sensitivity level 1 Sensitivity level 2 Sensitivity level 3 Sensitivity level 4

Workplaces

Housing, Hotel and holiday accommodation,

Institutional accommodation and education

Institutional accommodation

Parking areas Transport links

Prisons Very large outdoor use by public

Indoor use by public

Outdoor use by public

Source: Presentation by Themistoclis Kyriacou

The sensitivity levels are then adapted by taking into account the specific characteristics of the building and its size.

For example, a workplace with fewer than 100 employees will be rated as level 1 for sensitivity. However, a

workplace providing more than 100 jobs in a building of 3 levels or more will be rated as a sensitivity level 2

because of the number of people involved.

According to the sensitivity level of the buildings surrounding the area and the consequences of accidents reflected

in the zones, the following decision matrix is applied:

46 Presentation by Themistoclis Kyriacou, Labour Inspection Officer, Department of Labour Inspection, Cyprus, Land Use

Planning around Seveso establishments and sitting of new Seveso establishments

41


Table 4.9 Land use planning decision matrix for new and existing developments

Sensitivity Level

Existing developments New developments

Zone Ι Zone ΙΙ Zone ΙΙΙ Zone Ι Zone ΙI Zone ΙII

1 POWT PO PO POWT POWT PO

2 POWT POWT PO NO POWT POWT

3 NO POWT POWT NO NO POWT

4 NO NO POWT NO NO NO

Source: Presentation by Themistoclis Kyriacou

Czech Republic

The land use planning procedure for Seveso establishments revolves around the Regional Authority which is

responsible for the prevention of major accidents and is competent for discussing land-use planning applications

and procedures. When notified of a land-use procedure, the Regional Authority transfers an assessment of the risk

of a major accident as submitted by the operator in its safety report to the Construction Authority. Land use

planning decisions or construction permits cannot be issued if the assessment of the risk of a major accident has not

been carried out. The Dutch approach to defining acceptable levels of risk is recommended for operators47.

There are no defined guidelines on setting these zones. However, one example mentioned in a presentation from

the Competent Authorities included the following distances for a steelwork factory involving carbon monoxide

pipelines and storage48:

Internal emergency planning zone (450m / 1200 ppm); and

External emergency planning zone (1400 m / 200 ppm).

There are no set end point values to define a major accident in the Czech Republic49. Any significant release of a

dangerous substance, an explosion or fire can be understood as being a major accident. In addition, the Act

No.59/2006 Coll. on major accident prevention states that if the accident meets one of the criteria listed in the

legislation then it is major (see Section 2.3).

47 Survey response 48 Pavel Danihelka and Pavel Forint, Land-use planning and the SEVESO II directive in the Czech Republic, Ministry of the

Environment, LabR!SK project 49 Survey response

42


Greece

The Greek legislation does not require a quantitative risk assessment. However it is common that safety reports

include a risk assessment with a hazard identification, accident frequency calculation, definition of potential

consequences of accidents and risk estimation50. In Greece a typical identification of possible accident scenarios in

an establishment is based on a site-specific hazard analysis. In addition a review of past accidents that have

occurred in similar facilities is conducted. The approach focuses on the worst case scenario.

In order to determine hazard zones, threshold values regarding the level of thermal radiation, overpressure or toxic

dose that may give rise to undesirable effect have been adopted. Greece recommends a set of values that define

four zones within which specific undesirable effects would arise51. Each zone also represents the limits for certain

types of land use. It is compulsory that Zone I does not extend beyond the boundary of the establishment. The

zones defined are presented in Table 4.10.

Table 4.10 Type of development and zones in Greek land use planning

Zone Description Type of development

D Zone of domino effects (severe damage to equipment)

Minimum distance for location of other hazardous establishments

I Zone of multiple fatalities Minimum distance for manufacture, warehouse, open-space activities and recreational areas

II Zone of first death (1% lethality) Minimum distance for public roads, commercial activities, offices and low density housing developments

III Zone of first irreversible effects Minimum distance for residential development and institutional buildings (e.g. schools)

Source: P.D. Petrolekas and A. Charalambous, 2001, Land use planning considerations in the context of Seveso II Regulations

4.2.4 Restriction of Land use based on the probability of Damage

Figure 4.1 has been reproduced from a recent report looking at differences in land use planning approaches in

Member States. It summarises the criteria selected by three Member States to define societal risks and compare

them with the results of a research project (EP112). This corresponds to the risk-based or probabilistic approach to

land-use planning.

50 ShapeRisk Project, 2005, Synthesis document on WP2, Continuity of risk management from work place accident to major

accident 51 P.D. Petrolekas and A. Charalambous, Sept 2001, Land use planning considerations in the context of Seveso II Regulations

43


Figure 4.1 Social risk calculation in Flanders, the Netherlands and the UK


Details of Member States practices in relation to defining zones are provided below.

Belgium

Flanders Region

The assessment in Flanders is based on quantitative risk criteria which are the same for new and existing major

hazard establishments. The main aspects of the societal risk assessment are52 :

Employees and hired contractors at the establishment are not considered for the societal risk.

No societal risk criteria have been set for accidents involving less than 10 fatalities, as it is considered

that the location-based criteria must provide the necessary protection for these cases.

Establishments must show that all the necessary preventative measures have been implemented for

smaller accident scenarios (involving fewer than 10 fatalities).

For location-based risks (individual risk), Table 4.11 presents the thresholds associated with the land uses that are

permitted.

52 Niks Jan Dujim, 2009, Acceptance Criteria in Denmark and the EU

44


Table 4.11 Values defined for location based risks

Location-based risk per year Land use permitted

<10-5 Commercial activities permitted outside the establishment’s boundary line

<10-6 Residential areas (more than 5 residences) with no vulnerable areas (defined as schools, hospitals, nursing homes and associated land)

<10-7 All types of land use permitted


Walloon Region

The regulation on environmental permitting applies to new establishments or the modification of existing

establishments. For new installations near a Seveso site, the Walloon Region indicates, for each establishment, the

zones in which accident effects damaging to persons or property could occur; these are known as ‘vulnerable

zones’. The Major Risks and Accidents Unit (Walloon Region's coordination and evaluation unit) has issued a

methodology to evaluate the risk of a major accident.

The methodology used is probabilistic. It involves evaluating the risk of major accident combining the estimate of

probability of a dangerous event and the estimate of the effects of this event such as thermal radiation, overpressure

or toxic release53. The societal risk is not taken into account and the ceilings adopted are those which do not result

in irreversible effects for health.

Risk curves are calculated around Seveso establishment. The first 10-6 per year iso-risk curve is known as the

consultation zone. Any land-use in this zone is submitted to advice from the Competent Authority. For decision-

making a matrix has been established which combines the level of risk and the type of buildings and states whether

the permit should be issued or not. The matrix is presented in Table 4.12.

53 RIVM, 2011, An international comparison of four quantitative risk assessment Approaches Benchmark study based on a

fictitious LPG plant

45


Table 4.12 Decision matrix for land use based on individual risk

Type of land use

Individual risk

10 -3 to 10-4 per year

10-4 to 10-5 per year

10-5 to 10-6 per year

Type A – Buildings and technical units linked to the geography (e.g. water tower, waste water treatment, windmill)

OK OK OK

Type B – Buildings for a few people, mostly adult and autonomous With caution OK OK

Type C – Buildings for people, mostly adult and autonomous but without number restrictions

Not allowed With caution OK

Type D – Buildings for sensitive people with restricted autonomy Not allowed Not allowed With caution

Source: RIVM, 2011

Denmark

Until 2006, there were no specific guidelines concerning what constitute appropriate safety distances. In 2006, a

Circular setting a minimum distances for all establishments was sent by the Minister for the Environment to all

municipal councils (Circular No 37 of 20 April 2006 on land use planning). The Circular requires municipal

councils to take into account the risk of a major accident before any land use provision is made in a municipal or

local plan affecting areas within 500 m of an establishment.

Following this, the Danish Administration Practice has developed the zoning limitations as shown in the figure

below54.

Figure 4.2 Zones restrictions around Seveso sites

Source: Presentation by Morten R. Østergaard


DenmarkApplication of a Danish Administration Practice on Land Use Planning, 24 September 2012, Cyprus

Seveso

establishment

Zone 1

Zone 2

Iso risk curve 10-5/year

Iso risk curve 10-6/year

Zone 3

Maximum

consequence

distance

46


The zones are defined as follows:

Zone 1: Seveso establishment must have full right of disposal of area, which corresponds to an iso-risk

curve of 10-5 per year.

Zone 2: Neighbouring establishments can be accepted under certain conditions but no vulnerable

buildings can be authorised. The zone corresponds to an iso-risk curve of 10-6 per year.

Zone 3 (i.e. the maximum consequence zone): Neighbouring establishments and vulnerable objects

can be accepted provided that the criteria for societal risk curve are met. No buildings that play a role

in public emergency services or hosting people presenting difficulties for evacuation can be permitted.

The iso-risk curve for zone 1 is based on “location-based risk” that is defined as the risk that a person who is

continually present and unprotected at a given location will die. It does not include consideration of the exposure,

local protection or degree (duration) of presence. The maximum consequence zone is only calculated for scenarios

with a frequency higher than 10-9 per year and it is calculated from the impact level that can lead to life-threatening

and incurable injury55.

France

Since 2003, the French approach is a hybrid method that includes elements of a qualitative assessment in a

quantitative risk analysis. It is based on the identification of bow-tie, fault tree and event tree for many accident

scenarios and the analysis of the performance of the safety barriers put in place for each event. The key element

used for the assessment is the safety report, the results of which are directly used for decision making. The

following qualitative aspects are included56:

Frequency may be assessed using frequency classes;

Fixed end-point values are used to calculate consequence distances;

Various types of consequences such as heat radiation, toxicity and overpressure are assessed

separately (their frequencies are not summed); and

The effects of wind direction and speed are not considered. The safety zones are concentric circles

around the hazard source.

Land use around Seveso establishments is managed by the drafting of a technological risk prevention plan (PPRT),

which evaluates the probability, the intensity of the phenomena and the kinetics for each scenario. It is a flagship

measure of the legislation which aims at protecting people by acting on the existing urbanisation and by

controlling the future land-use planning in the vicinity of top-tier Seveso establishment57.


DenmarkApplication of a Danish Administration Practice on Land Use Planning, 24 September 2012, Cyprus 56 Niks Jan Dujim, 2009, Acceptance Criteria in Denmark and the EU 57 Clément Lenoble, Clarisse Durand, Introduction of frequency in France following the AZF accident, Journal of Loss

Prevention in the Process Industries, 24 (2011) 227-236

47


Endpoint values are used to calculate the intensity of the phenomena for each scenario. The gravity of the effects is

defined by using a scale which depends on the number of victims for each type of effect assessed. The scale is

presented in Table 4.13, the numbers represent number of people affected by the accident.

Table 4.13 Scale of gravity depending on the number of people involved.

Consequence Significant lethal effect Lethal effect Irreversible effect

Seriousness

Disastrous >10 >100 >1000

Catastrophic 1-10 10-100 100-1000

Major <1 1-10 10-100

Serious 0 <1 1-10

Moderate 0 0 <1


Other elements are assessed, including the probability. For this a scale of five categories has been adopted to guide

the assessment, and is presented in Table 4.14.

Table 4.14 Range of probability scale

Probability class

Quantitative frequency assessment (per year)

E 0 to 10-5

D 10-4 to 10-5

C 10-3 to 10-4

B 10-2 to 10-3

A 10-2

Source: Clément Lenoble, Clarisse Durand, Introduction of frequency in France following the AZF accident

Once all the elements have been characterised, they are included in a risk matrix defining three levels: unacceptable

(i.e. risk is too high, the installation cannot be authorised), acceptable (i.e. authorisation can be given) and

intermediate (i.e. authorisation can be given after verification that all practicable risk control measures have been

put in place, ALARA).

48


Table 4.15 Risk matrix in French assessment

Probability

Gravity

E D C B A

Disastrous ALARA No No No No

Catastrophic OK ALARA No No No

Significant OK ALARA ALARA No No

Serious OK OK ALARA ALARA No

Moderate OK OK ALARA ALARA No


The technological risk prevention plan (PPRT) establishes specific zones as follows:

A dark red zone on which construction is banned and the state can expropriate;

A light red zone where new construction is banned but existing industrial buildings can be extended if

they are protected;

A dark blue zone where new construction is possible depending on the limitations on use or the

protection measures; and

A light blue zone where new construction is possible depending on minor limitations.

The zones are established in relation to the ‘aléas level’ and cumulative probabilities as presented in Table 4.16.

The aléas are defined as the combination of the probability of a dangerous phenomenon and the potential intensity

of its effects. They are calculated for each point of the territory and for each type of effects (thermal radiation,

overpressure and toxic release)58. The cumulative probability is defined in accordance with the information


58 Clément Lenoble, Clarisse Durand, Introduction of frequency in France following the AZF accident, Journal of Loss

Prevention in the Process Industries, 24 (2011) 227-236

49


Table 4.16 Application of zoning in PPRT

Maximum intensity of the toxic, thermal or overpressure effects on human at a given point

Very serious (significant lethal)

Serious (Lethal)

Significant (Irreversible)

Indirect

Cumulative probability of dangerous phenomena at a given point

>D 5E to D

<5E >D 5E to D

<5E >D

5E to D

<5E All

Aléa level VH+ VH H+ H M+ M Low

Zoning in PPRT Dark red Light red Dark blue Light blue


Three aléas maps are drawn, one for each effect (thermal radiation, overpressure and toxic release). The zones are

defined as follows:

Red zones are “ban” zones where future construction is banned. Dark red areas are defined for

expropriation or relinquishments and light red zones for relinquishments.

Blue zones are “limitation” zones, within which protective measures on the future or existing

buildings can be compulsory.

The figure below presents a simplistic representation of the zones as defined by the PPRT process.

Figure 4.3 Zone definition from the PPRT process


50


Italy

The risk assessment includes the following steps: the identification, classification and localisation on the map of

vulnerable elements (population, environment, facilities, etc.); the comparison of the defined impact area with the

map of vulnerable elements; the identification of all situations in which the vulnerable elements are located within

the limits of the impact area; and a compatibility judgment for each situation59. The judgment is based on a rating

of the vulnerability of the elements and the gravity of the impact in accordance with specific compatibility tables.

Table 4.17 Compatibility table for LUP in Italy

Frequency /year

Effects

High lethality Beginning of lethality

Heavy injury Light injury

<10-6 DEF CDEF BCDEF ABCDEF

10-4 – 10-6 EF DEF CDEF BCDEF

10-3 – 10-4 F EF DEF CDEF

>10-3 F F EF DEF

Source: Survey response

In this table the letters A, B, etc. stand for specific building category/ type of land use. For example D is residential

area with maximum index of construction 0.5 m3/m2 or area in which there are churches, local markets or similar

activities. F designates that area within the boundaries of the establishment or adjacent to the plant in which no

activity is authorised. Italian legislation (i.e. D.M., 2001, Decree of Italian Ministries 09.05.2001 Minimum safety

requirements relating to town and country planning for areas affected by major accident hazard establishments ,

Official Gazette of the Italian Republic, 138 - S.O. 151, 16.06.2001) describes in details the content of each

building category.

The Netherlands

The approach taken in the Netherlands is risk-based and the assessment is conducted through a Quantitative Risk

Assessment (QRA), for which a methodology has been adopted by the Competent Authorities (i.e. the Purple Book

which has now been replaced by the Bevi). As part of the QRA, three level of individual risk are defined (i.e.

acceptable, as low as reasonably acceptable and non-acceptable).

The Netherlands makes a distinction between individual and societal risk which are defined as follows:

59 JRC, 2008, Overview of Roadmaps for land-use planning in selected Member States

51


Individual risk is the likelihood of a person who lives unprotected for 24 hours a day, 365 days a year

at a particular site dying as a result of an accident involving dangerous substances ;and

Societal risk is the probability that a group of more than N persons gets killed due to an accident

deriving from a hazardous installation.

The individual risk is location-based; it is expressed in frequency terms. It includes elements such as the initial

accident frequency, the probability of development, probability of the effects and damage. It is presented in iso-

risk contours over a topographic map of the surrounding on an establishment. The national legislation includes a

set of endpoint values for ‘tolerable’ which is a frequency of 10-6 events/year limit. Figure 4.4 represents an

example of this.

Figure 4.4 Representation of location risk in the Netherlands

Source: Robbert Plarina, 2011

The societal risk is expressed in a number of fatalities per year and is presented as a curve of the number of victims

against the frequency of occurrence. There are not values set in the legislation, and the zones are defined on a case

by case basis. Figure 4.5presents an example of this.

52


Figure 4.5 Representation of societal risk in the Netherlands

Source: Robbert Plarina, 2011

The probabilistic approach allows a wider range of modifications to be quantified and reduce the zones, however it

requires additional data (i.e. on failure frequencies particularly) which can be difficult to collect60.

The UK

In the UK, the LUP decisions are taken by the Local Planning Authorities, and advice is produced by the Health

and Safety Executive (HSE). Consequences based zones are defined; the consultation zone is the limit of HSE

interest. Within the consultation zone, three zones are defined as follows:

Inner zone: 10 cpm (10-5 per year), 1800 TDU, 600 mbar;

Middle zone: 1 cpm (10-6 per year), 1000 TDU, 140 mbar; and

Outer zone: 0.3 cpm (3x10-7 per year), 500 TDU, 70 mbar.

The frequency (expressed in chance per million) represents the change per million per year of receiving a

dangerous dose. A decision matrix is then established to identify the developments that are allowed in each zone in

accordance with their sensitivity level.

The HSE defines four sensitivity levels:

60 Presentation by Robbert Plarina, 25 May 2011, Risk based External Safety Regulations in the Netherlands, Seveso

Conference Stockholm.

53


Level 1 – Normal working population

Level 2 – General public at home and involved in normal activities

Level 3 – Vulnerable members of the public (children, those with mobility difficulties, those unable to

recognise physical danger)

Level 4 – Large examples of Level 3 or very large outdoor examples of Level 2

These levels of sensitivity correspond to four types of developments:

Type 1 – People at work or parking

Type 2 – Developments for use by the general public

Type 3 – Developments for use by vulnerable people

Type 4 – Very large and sensitive developments

As a general principle the sensitivity level is decreased by one for small examples of a type of development and

increased for large and very large examples of a type of development or where particular features of the

development increase the risk to the population. Table 4.18 provides specific example of cases where negative

advice can be issued for specific type of activities.

Table 4.18 HSE assessment per type of building

Type of activities HSE assessment

A: Residences, hotels, holiday accommodation Negative advice when more than 25 people are exposed to individual risk over 10-5 per year or more than 75 people are exposed to 10-6 per year

B: Workplaces, enterprises, parking areas Negative advice only if the risk from the establishment exceed the normal risk for workplace accidents

C: Shops, meeting rooms, sport and leisure No set rules, advice will be consistent with the principles for category A. Cut-off figures of 100 or 300 people are used for each risk scenario

D: Highly vulnerable or large facilities ( hospitals, schools, large category C facilities involving more than 1000 people)

As for A but the risk criteria are set lower (1/3 of the acceptance criteria) so 0.3 x 10-5 and 0.3 x 10-6


The HSE gives its advice in accordance with the decision matrix reproduced in Table 4.19. DAA stands for ‘don’t

advise against’ the development and AA for ‘advise against’ the development61.

61 HSE’S current approach to land use planning (LUP), http://www.hse.gov.uk/landuseplanning/lupcurrent.pdf

54


Table 4.19 Decision matrix for HSE in UK

Level of sensitivity Development in Inner Zone

Development in Middle Zone

Development in Outer Zone

1 DAA DAA DAA

2 AA DAA DAA

3 AA AA DAA

4 AA AA AA

Source: HSE, HSE’S current approach to land use planning (LUP) (http://www.hse.gov.uk/landuseplanning/lupcurrent.pdf)

The HSE has studied societal risk extensively62, but does not have prescriptive criteria it has indicated that it is

working on determining criteria for societal risk. One criterion used is that ‘the risk of an accident involving 50 or

more deaths from a single event should be seen as unacceptable if the expected frequency is greater than once

every 5,000 years’. This is the criteria used for representing the UK in Figure 4.1.

4.3 Other criteria for defining major accidents

As it has been highlighted in Task 4, analysis of past accidents can help in understanding the links that can be made

between the hazard category of a substance and the dangerous phenomena that may be generated further to an

accident involving that substance. It can also help in identifying the type of substances that have been involved in

major accidents as well as recurrent trends or patterns of accidents.

As a result, one step of the assessment methodology could be to show, through a review of the existing accidents

database (e.g. eMARS and ARIA), that the substance proposed has not been involved in any previous industrial

accident. Some databases also record ‘near-misses’ and it might also be appropriate to show that the substance has

not been involved in any ‘near-miss’ cases. However, as set out in the Task 4 report, the absence of past accidents

involving a substance is not on its own sufficient to rule out the possibility of future major accidents.

62 See for example http://www.hse.gov.uk/societalrisk/

http://www.hse.gov.uk/societalrisk/background-information.htm

55


5. Recommendations on Determining Potential for a Major Accident

5.1 Overview

Following the analysis presented in Sections 3 and 4 the following suggestions are made for the use of the

thresholds, cut-off values and safety distances in the context of the assessment methodology.

Several elements have been researched in order to help further understand of the concept of ‘major accident’

beyond the existing definition of Article 3. Whilst it is evident that both Annex VI criteria and safety distances

used in the Member States do not provide a definition of ‘major accident’, they both include elements that may be

helpful for some people in informing the decision making process in the context of Article 4.

5.2 Annex VI of the Seveso Directive

Annex VI lists criteria that characterise major accidents to be reported by Member States to the European

Commission. In the context of the assessment methodology, Member States could compare the results of the

modelling stage (i.e. the effect distances) with some of the criteria for reporting in Annex VI (i.e. those criteria that

are relevant to the effects being studied). Whilst a direct comparison is not possible (the modelling would provide

distances for effects whereas Annex VI lists characteristics of accidents), this step would be the opportunity for the

Member State to demonstrate that the criteria of Annex VI cannot be credibly met for the substance considered. If

it seems credible that at least one of the criteria described in Annex VI could be met, then the substance cannot be

considered as not being able to create a major accident. In contrast, if it seems credible that none of the criteria of

Annex VI could be reached, then further assessment may be required to conclude that there is no potential for a

major accident.

However, this on its own is not necessarily sufficient to demonstrate that a major accident cannot occur. Annex

VI includes criteria for notifying a major accident to the Commission which is not identical to criteria for defining

what is considered to be a major accident. It is important to highlight that the use of Annex VI described here is

limited only to the purpose of the assessment methodology. Respondents to the survey circulated to Seveso experts

and Competent Authorities during the initial phase of this project and participants at the project workshop have

indicated that using the criteria of Annex VI for defining a ‘major accident’ was not a suitable approach on its own.

However, it could provide a useful starting point and so assessors may wish to take these criteria into account, as

one of a number of elements, when drawing conclusions on whether a major accident is impossible in practice for

an Article 4 candidate substance.

5.3 Level of harm

One essential aspect of defining a major accident is deciding on the level of harm which is considered to represent

effects of a major accident.

56


A review of some Member States’ practices by the JRC considered different levels of injury for different types of

dangerous phenomena. This review concluded that an ‘irreversible injury’ can correspond to lethality in some

Member States (e.g. Estonia and Poland see Table 3.4). Level 4 (irreversible injury) may in some instances be the

point at which accidents would have effects that equate to a major accident.

Choosing ‘reversible injury’ as the level of harm at which effects of an accident are considered major would be a

strict interpretation. The reversible effects threshold could be readily reached for almost any accident scenario,

even for substances without classification leading to coverage by the Seveso III Directive.

It is important that the level of harm defining a major accident in accordance with the assessment methodology is

agreed by Member States.

It is also important to take into account the overlap between the Seveso Directive, which covers major accidents,

and the harm that may occur as a result of industrial accidents which only affect a small number of workers on-site

covered by other occupational safety and health legislation in the EU (where accidents may not be major).

As a conclusion, for the assessment methodology, it is not considered that the scale of effects can be considered in

isolation. However, the review of member states’ approaches to defining levels of harm may be an element that

assessors wish to take into account in assessments under Article 4. Once again, member states and others are free

to use or disregard this information in their considerations under Article 4. The approaches considered in this

report are not binding or prescriptive.

5.4 Effects thresholds

The review of Member States’ practices has highlighted a range of existing thresholds for thermal radiation,

overpressure and toxic exposure that are used at national level for defining what constitutes a major accident and

for land use planning purposes. Two options are possible for taking these into account in the assessment

methodology:

Conduct the modelling phase of the assessment using the lowest threshold values for relevant effects

amongst the Member States. For example, this would mean that for modelling thermal radiation

effects, the Italian values for Level 3 (i.e. reversible effects) would be retained (3 kW/m2); or

An alternative is to use the default values that have been defined by the pan-European ARAMIS

project. In some cases, these values match those of the most stringent Member States. The advantage

of using the ARAMIS values is that these thresholds are likely to be more readily accepted by Member

States as representing a consensus view, rather than adopting a specific Member State’s approach.

For the assessment methodology, these values may be of use in deciding which effects thresholds should be used

when assessing the consequences of an accident involving a candidate for Article 4. However, once again,

assessors are free to adopt any other approaches that they consider appropriate, recognising that these will need to

be justified to, and accepted by, the Commission and other member states.

57


5.5 Land use planning approaches

The review of Member States’ approaches to zoning and setting safety distances in the context of land-use planning

around Seveso establishments has highlighted a lot of variation.

Whilst it is recognised that safety distances used in the context of land use planning do not correlate directly with

distances at which a major accident is concluded to occur (or not), these approaches were covered in the project as

one of the only source of information with quantitative values related to distances and effects of accidents at Seveso

establishments. The aim was to determine whether and how these approaches might guide the interpretation of the

notion of ‘major accident’ in the context of Article 4.

In the context of the assessment methodology under Article 4, one approach would be for the reversible effect

distance from the modelling results to be compared to the shortest distance used in land use planning for similar

effects (as this would provide a more protective/conservative approach). The choice of the distance depends on the

type of substance under assessment and on the type of dangerous effects that may be generated. Reference distances

could mirror those used by Member States, an example of which is summarised in the table below (for Catalonia,

which has the shortest distances for the phenomena listed).

Table 5.1 Example of possible reference distances in the context of Article 4

Dangerous phenomenon Effects to consider Possible distance (m)

Toxic cloud Toxic effects 350

BLEVE Thermal and overpressure effects

200

Fires, explosions Thermal and overpressure effects

200

Flammable cloud, explosion, jet fire Thermal and overpressure effects

100

Pool fire Thermal effects 50

Spills causing pollution - 50

Source: Distances set by Spain (Catalonia)

If the modeled reversible effects distance is lower than the corresponding safety distance, it seems more likely that

a major accident cannot occur. If the reverse situation is observed (i.e. the modelled reversible effects distance is

higher than the corresponding safety distance), a major accident is less likely. However, these distances are clearly

too ‘blunt’ an instrument to be used directly in determining whether a major accident is possible. For example, a

dispersion causing toxic effects could clearly cause a major accident (and severely affect many people) at distances

far less than 350 metres.

58


It is recognised that shorter distances used in the context of land use planning (e.g. for restriction of development)

are less ‘protective’ than greater distances. However, in the context of Article 4, if significant effects occur only up

to a short distance from the establishment (e.g. based on modelling of a worst-case scenario), this indicates

relatively lower potential for a major accident. In practice, choosing a distance at which no major accident hazard

is considered possible is a largely arbitrary exercise, and a case-by-case judgement will need to be made by the

assessor.

While the distances used in land-use planning amongst the member states give a useful indication of the range of

distances considered relevant for determining major accident potential, they are not in themselves directly relevant

in determining whether a major accident can occur or not.

It is apparent from the workshop for this project that many experts in the field do not consider land use planning

distances to be a suitable basis for determining whether a major accident can occur in practice. It is also clear that

there are not other reference distances available in the existing literature that allow one to determine – in a general

way – whether a modelled accident could be considered major or not. This is therefore an area where further work

may be required before any consensus can be reached on whether a modelled accident can be considered to be

major or not in the context of Article 4.


Appendix A References

Reports

ACUTEX, January 2006 , Methodology to develop AETLs

ARAMIS, 2004, Accidental risk assessment methodology for industries in the context of the Seveso II Directive,

WP2, Severity evaluation

Institute for Systems Informatics and Safety, 1999, Guidance on Land Use Planning as required by Council

Directive 96/82/EC (Seveso II)

Clément Lenoble, Clarisse Durand, Introduction of frequency in France following the AZF accident, Journal of

Loss Prevention in the Process Industries, 24 (2011) 227-236

JRC, 2005, Guidance on the preparation of a safety report to meet the requirements of Directive 96/82/EC as

amended by Directive 2003/105/EC (Seveso II), Institute for the Protection and Security of the Citizen

JRC, 2006, Land-Use planning Guidelines in the context of Article 12 of the Seveso II Directive 96/82/EC

JRC, 2007, Risk Mapping of Industrial Hazards in New Member States

JRC, 2008, Overview of Roadmaps for land-use planning in selected member States

Niks Jan Dujim, 2009, Acceptance Criteria in Denmark and the EU

I.A. Papazoglou, Quantitative Risk Assessment For Accidents At Work In The Chemical Industry And The Seveso

II Directive, System Reliability and Industrial Safety Laboratory

P.D. Petrolekas and A. Charalambous, 2001, Land use planning considerations in the context of Seveso II

Regulations

O. Salvi, Risk assessment in decision making related to land-use planning (LUP) as required by the Seveso II

directive

Pavel Danihelka and Pavel Forint, Land-use planning and the SEVESO II directive in the Czech Republic, Ministry

of the Environment, LabR!SK project

ShapeRisk Project, 2005, Synthesis document on WP2, Continuity of risk management from work place accident to

major accident

Presentations

Presentation by Themistoclis Kyriacou, Labour Inspection Officer, Department of Labour Inspection, Cyprus. Land

Use Planning around Seveso establishments and sitting of new Seveso establishments


Presentation by Priit Laaniste, Seveso II and land-use planning in Estonia, Estonian Ministry of the Interior, November 2007.

Presentation by Morten R. Østergaard, Danish EPA, Land use planning in the Habour area in the municipality of Aarhus,

DenmarkApplication of a Danish Administration Practice on Land Use Planning, 24 September 2012, Cyprus

Presentation by Robbert Plarina, 25 May 2011, Risk based External Safety Regulations in the Netherlands, Seveso

Conference Stockholm

Presentation by Hans-Joachim Uth , Zoning for Land use Planning in Germany and Europe, Federal Environmental

Agency Dessau (FRG)

RIVM, 2011, An international comparison of four quantitative risk assessment Approaches Benchmark study based

on a fictitious LPG plant

Guidelines

Advanced Technologies and Laboratories International, Protective action criteria,

http://www.atlintl.com/DOE/teels/teel/teel_pdf.html

American Environmental Protection Agency, Acute Exposure Guidelines Levels,

http://www.epa.gov/oppt/aegl/pubs/define.htm

American Industrial Hygiene Association, ERPG Guidelines, 2013 https://www.aiha.org/get-

involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPGIntroText.pdf

European Centre for Ecotoxicology and Toxicology of Chemicals , http://www.ecetoc.org/index.php

Generalitat de Catalunya Departament d’Interior, Relacions Institucionals i Participació Direcció General de

Protecció Civil Subdirecció General de Programes en Protecció Civil, November 2009, Land use and spatial

planning: criteria for risk management

Health and Safety Executive, Toxicity levels of chemicals, http://www.hse.gov.uk/chemicals/haztox.htm

HSE, HSE’S current approach to land use planning (LUP), http://www.hse.gov.uk/landuseplanning/lupcurrent.pdf.

INERIS, Portail Substances Chimiques, Seuils de toxicite, http://www.ineris.fr/substances/fr/page/23

National Institute for Occupational Safety and Health, pages on IDLH, http://www.cdc.gov/niosh/idlh/default.html

HSE, 2006, A guide to the Control of Major Accident Hazards Regulations 1999 (as amended) (L111)

Service Public Fédéral, Emploi, Travail et Concertation Sociale, Accident majeur,

http://www.emploi.belgique.be/defaultTab.aspx?id=6264

http://www.hse.gov.uk/landuseplanning/lupcurrent.pdf