Air Pollution and GIS

ETHEKWINI AIR QUALITY MONITORING NETWORK

ANNUAL REPORT

2005

POLLUTION CONTROL SUPPORT SECTION (ETHEKWINI HEALTH DEPARTMENT)

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POLLUTION CONROL SUPPORT SECTION

ANNUAL REPORT

AIR QUALITY MONITORING NETWORK 2005

DATE

PREPARED BY

_________ ___________

___________ ___________

ACCEPTED BY

__________ S CHETTY

Note: The original signed copy will be stored in the Pollution Control Support Section office.

eThekwini Air Quality Monitoring Network Annual Report 2005

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EXECUTIVE SUMMARY

The eThekwini Municipality commissioned the continuous air quality monitoring network in December 2003, as one of the major elements of its Air Quality Management System. The primary objectives of the network are to quantify the quality of air in South Durban, measure compliance with air quality standards and provide a means of verification for dispersion models. The network consists of twelve air monitoring stations, three of which are background stations, and six meteorological stations. The network instruments continuously measure the priority pollutants sulphur dioxide (SO2), oxides of nitrogen (NOx), particulate matter less than 10 microns (PM10), ozone (O3) and carbon monoxide (CO). In addition, measurements of total reduced sulphur (TRS) are also conducted. All analysers are designated under USEPA regulations as equivalent methods. The operation of the network and the management of data are aligned to internationally prescribed quality control standards and guidelines. Incorporated into the operation of the network are weekly span and zero checks and quarterly calibration audits. The raw five minute real-time data generated by the network is subject to technical and logical quality control. The network achieved an overall data capture rate of 90% for pollutant data and 93.3% for meteorological data for 2005. This compares favourably with the target data capture of 90%. The results of the quarterly calibration audits pointed to a general improvement in the performances of the gas monitors from 2004 to 2005. Fewer of the SO2 and NOx monitors experienced span drifts that were beyond the limits of acceptability. Air quality compliance was assessed by comparing the results of the monitoring with the limit values contained in SANS 1929. The results highlighted industries as the major source of SO2 in South Durban. Southern Works is again the SO2 hotspot station, having recorded an annual average of 16.2 ppb versus an annual limit value of 19 ppb. This compares favourably with the annual average of 22.2 ppb that was recorded for 2004. The station has thus made the transition to compliance. This is primarily attributable to the commissioning of the SO2 scrubbers at Mondi in May 05. The Southern Works station also recorded 14 exceedances of the daily ten minute SO2 limit value compared to 34 exceedances for 2004 and 240 exceedances of the 10-minute SO2 limit value compared to 796 exceedances for 2004. The SO2 monitoring results at Wentworth demonstrated a reduction from 16.3 ppb (2004) to 12.2 ppb (2005). TRS, though not classified as priority pollutant, was measured at Settlers and Southern Works to address the issue of odours in Merebank. TRS values were compared with the derived European Union based 30-minute odour threshold of 7.8 ppb. The total of 2141 exceedances of the odour threshold at Southern Works versus the 257 for Settlers confirms Southern Works as the TRS hotspot in South Durban. To address this problem, the Southern Waste Water Treatment Works and Mondi, two major sources of TRS in Merebank, have embarked on H2S reduction programmes. The monitoring results suggest that traffic contributes significantly towards PM10 emissions. The Ganges station, located along the Southern Freeway recorded an annual average of 43.1 µg/m3, which exceeded the annual limit value of 40 µg/m3, however there was a decrease compared to annual average of 46.4 µg/m3 recorded for 2004. The monitoring results have again confirmed that PM10 is a pollutant of concern in the city as other stations also recorded annual averages that were high, though not exceeding the annual limit.


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The behaviour of the NO2 data closely resembled that of PM10 in that traffic stations again recorded the highest values. The Warwick and Ganges stations both recorded the highest annual averages of 21 ppb, with the annual limit value being 21 ppb. CO, a known traffic pollutant was measured solely at the Warwick station. Although annual limit values for CO do not exist, 1-hour and 8-hour limit values do exist. There were three 1-hour exceedances and seven 8-hour exceedances for 2005. The other pollutant measured was O3, which is classified as a priority pollutant. An annual limit value is not in place for O3. However, based on the target values in Table 4.1, one 1-hour and eleven 8-hour exceedances were recorded at Alverstone. There were no exceedances at Wentworth. The Wentworth O3 analyser was temporarily moved to Warwick to measure O3 levels in traffic hot spot for a period of three months. The average O3 concentration for the three months at Warwick was 5.8 ppb, which is significantly lower than the average O3 levels for Wentworth (14.7 ppb). The six meteorological stations measure a range of parameters that include wind speed, wind direction, ambient temperature, relative humidity, net radiation and rain. The wind roses confirm the north-easterly and south-westerly directions as being the dominant wind directions. Pollution roses for the year were constructed to indicate prevailing sources are dominant. An analysis of the roses indicated that the highest SO2 concentrations measured at Southern Works was from the direction of Mondi. Similarly, the highest SO2 concentrations measured at Settlers was from the direction of Engen. An analysis of the PM10 pollution rose at Ganges, a station which recorded an annual exceedance of the PM10 limit value, revealed that the traffic hotspots were the major contributors to high levels recorded at the Ganges station. Industrial pollution is currently being addressed by issuing polluting industries with permits that set reduction targets to drive down emission levels. The schedule trade permitting process is a robust process and is certain to result in an improvement in overall air quality. However, the challenge that lies ahead in addressing traffic pollution, which the results of monitoring has proved to be a source of concern, is going to require a more integrated approach involving all levels of government, the public and the private sector.


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NOMENCLATURE Symbol Definition LV Limit value TV Target value SO2 Sulphur dioxide NO2 Nitrogen dioxide NO Nitrogen oxide NOx Oxides of nitrogen CO Carbon monoxide O3 Ozone PM10 Particulate matter of less than 10 microns TRS Total reduced sulphur H2S Hydrogen sulphide TSI Technology Services International of Eskom SANAS South African National Accreditation System US EPA United States Environmental Protection Agency WHO World Health Organisation EU European Union SANS South African National Standards DEAT Department of Environmental Affairs and Tourism ppb Parts per billion ppm Parts per million


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TABLE OF CONTENTS 1. INTRODUCTION 1 2. DATA RECOVERY 2 2.1 QUALITY CONTROL 2 2.2 DATA CAPTURE 2 2.2.1 Pollutant Data 2 2.2.2 Meteorological Data 3 3. CALIBRATION AUDITS 4 4. MONITORING RESULTS AND DISCUSSIONS 5 4.1 SULPHUR DIOXIDE 5 4.2 PARTICULATE MATTER 8 4.3 OXIDES OF NITROGEN 11 4.4 OZONE 13 4.5 CARBON MONOXIDE 15 4.6 TOTAL REDUCED SULPHUR 16 4.7 METEOROLOGICAL RESULTS 18 4.7.1 Wind Roses 18 4.7.2 Stability Frequency 20 4.7.3 Pollution Roses 21 5. CONCLUSIONS AND RECOMMENDATIONS 24 APPENDIX 1 - CALIBRATION AUDIT RESULTS APPENDIX 3 – DIRECTIONS OF SOURCES FROM MONITORING STATIONS APPENDIX 3 – STATION DESCRIPTIONS

a) PROSPECTON b) SOUTHERN WORKS c) SETTLERS d) GANGES e) GROSVENOR f) KING EDWARD g) WARWICK h) WENTWORTH i) CITY HALL j) JACOBS MET k) ALVERSTONE l) JACOBS m) SAPREF n) HARBOUR


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APPENDIX 4 – INSTRUMENTATION

a) SO2 FLOURESCENT ANALYSER b) NO2 CHEMILUMINESCENT ANALYSER c) O3 ULTRAVIOLET ANALYSER d) PM10 TEOM ANALYSER e) CO INFRA-RED ANALYSER f) AUTOMATIC WEATHER STATIONS g) DATA ACQUISITION


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1. INTRODUCTION

The eThekwini Municipality established a modern air quality monitoring network in the South Durban Basin in December 2003. The basin is located on the eastern seaboard of South Africa and has a mix of heavy industrial activity and residential settlements in close proximity. In response to many decades of struggle for cleaner air, an inter-governmental process established the air quality monitoring network as one of many strategic projects within the Multi-point Plan for the basin. The plan is aimed at improving air quality to meet health based standards. The main objective of the network is to provide a quantitative measure of air quality, measure compliance with air quality standards and provide a means of verification for dispersion models. The network was designed by an expert team from the eThekwini Health Department under the technical guidance of NILU, the Norwegian Institute for Air Research. The air quality monitoring network, whilst primarily focused in the South Durban basin, also extends into the city centre and three background sites. Each of the stations measures a range of pollutant and meteorological parameters in five minute averages. The two main sources of air pollution that the network aims to target are industrial and traffic pollution. The pollutants measured include sulphur dioxide, total reduced sulphur, oxides of nitrogen, particulate matter (PM10), ozone and carbon monoxide. The network incorporates the latest technology in continuous air quality monitoring. The network currently consists of twelve air monitoring stations and six meteorological stations. The three background stations are located at Alverstone, Congella and Prospecton. The network is dynamic in nature as new stations could be added and obsolete stations removed.

This annual report focuses on the operation of the network for 2005. Comparisons were made with previous years’ data were applicable.

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2. DATA RECOVERY 2.1 QUALITY CONTROL

Several measures are in place to ensure that the air quality monitoring network meets with internationally prescribed quality control standards as local standards are currently not in place. The stations are serviced weekly by the staff of the Pollution Control Section. During weekly station visits, level 1 zero and span checks (two-point analyser calibration) are performed to ensure that analyser drift is within acceptability limits. Analysers are adjusted to read the correct standard gas concentrations when responses are found to be outside of acceptability limits. In addition to the weekly level 1 zero and span checks, quarterly multi-point calibrations are also carried out by Eskom, a SANAS accredited calibration laboratory. Multi-point calibrations are used to verify the linearity of the analysers and consist of four test concentrations, including zero concentration, a concentration at 80 % of full range and two intermediate concentrations. All procedures used are SANAS approved and the gases are traceable.

2.2 DATA CAPTURE

Data capture is an indicator of station and equipment reliability, and is a key performance indicator of the overall network performance. The data capture percentage target for the network has been set at 90%.

2.2.1 Pollutant Data

SITE SO2 NOX PM10 CO TRS O3Prospecton 78.4 Southern Works 96.6 89.0 87.0 Settlers 89.5 72.5 Ganges 97.8 94.9 95.9 Grosvenor 83.8 King Edward 88.5 85.5 Warwick 92.2 93.8 62.3 Wentworth 97.5 95.3 96.6 87.5 City Hall 95.0 88.7 Alverstone 96.4 Ferndale 93.3 90.8 89.3 Jacobs 98.5 90.5

TABLE 2.1 – DATA CAPTURE PERCENTAGES FOR POLLUTANT MEASUREMENTS

The data in Table 2.1 serves as the comparative basis for the calculation of the overall data capture target for pollutant measurements of 90%. The majority of gas monitors achieved data capture rates in excess of 90%. Operational problems were experienced with the TRS analysers, especially at Settlers, where an old API analyser needed frequent repairs. Operational problems were also experienced with the Monitor Lab NOx analysers. The

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ozone generators of these analysers fail at a high rate. The problem was initially believed to be related to the high humidity levels in Durban, but have recently also been found to be prevalent in Norway.

2.2.2 Meteorological Data

SITE WS WD T ∆T RH BP SR RAINSouthern Works 98.0 99.4 99.4 99.4 99.4 99.4 Grosvenor 98.2 98.2 82.1 89.8 45.4 Wentworth 94.8 85.7 86.4 92.1 89.0 Jacobs 99.5 91.4 Sapref 100 100 83.3 Harbour 99.0 99.0 99.0 99.0 99.0

TABLE 2.2 – DATA CAPTURE PERCENTAGES FOR METEOROLOGICAL MEASURMENTS

The overall data capture rate for meteorological measurements from the data in Table 2.2 was 93.3%. The meteorological instruments have generally proven to be reliable and free from breakdowns.

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3. CALIBRATION AUDITS

Quality control activities are used to ensure that measurement uncertainty is maintained within acceptable criteria. One of the important quality control procedures for the operation of an air monitoring network is the 3-monthly calibration audit. The calibration audit is used to validate and document the accuracy of the data generated by the gas analysers. The audit procedure consists of diluting a standard gas from a gas cylinder to a known concentration with clean, dry air. The dilution is performed by utilising a dynamic calibrator. Eskom TSI is a SANAS accredited laboratory that has been tasked with performing the calibration audits. All calibrations are carried out in compliance with SANAS approved procedures. Furthermore, the calibration procedures conform to USEPA requirements. Appendix 1 contains a summary of the calibration audit results for the year. Highlighted in red are the calibration results that failed to comply with quality control acceptability limits. The following is a brief assessment of these results:

• Generally, the results of zero checks showed minimal drift from zero. The one notable exception was the SO2 analysers at Settlers which produced a zero drift of 45 ppb high during the January 2005 audit. This was attributed to a temperature problem with the oven of the analyser, which has subsequently been resolved as can be seen from the audits done in May, July and October.

• However, the results of span checks showed a variation in results, with several analysers performing acceptably and other recording drifts that were out of the range of acceptability of ± 15%. These included both the SO2 and NOx analysers. However it must be noted that the span checks for the TRS analysers had improved.

• The data produced by these analysers was more closely examined. In addition, the weekly span results were assessed to track the performance of the analysers. Where considered necessary, data was either adjusted or invalidated for the period of interest.

• The performances of most of the analysers had gradually improved with time. This is consistent with the theory that analysers need to be ‘run in’ before eventually settling down to an acceptable performance as can be seen from the tables in Appendix 1.

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4. MONITORING RESULTS

Table 4.1 below contains the most recent limit and target values of criteria pollutants, as contained in SANS 1929, and derived as an output from the DEAT standard setting process. Air quality measurements will be evaluated against these limit (and target values) that are expected to eventually be adopted as the ambient air quality standards for South Africa. One of the pollutants measured, total reduced sulphur (TRS), and has not been considered in the standard setting process. For discussion purposes, a value of 7.8 ppb (based on EU odour threshold for H2S) will be used.

PARAMETER AVERAGING

PERIOD UNITS LIMIT VALUE COMMENTS

10-min ppb 191 WHO based 24-hour ppb 48

SO2

1-year ppb 19 1-hour ppb 106 NO2 1-year ppb 21 24-hour µg/m3 75 1-year µg/m3 40

24-hour µg/m3 50 Target Value

PM10

1-year µg/m3 30 Target Value

1-hour ppb 102 Target Value O3 8-hour ppb 61 Target Value 1-hour ppm 26 CO 8-hour ppm 8.7

TABLE 4.1: LIMIT VALUES FOR PRIORITY POLLUTANTS (SANS 1929) 4.1 SULPHUR DIOXIDE

SO2 is a colourless gas that has a pungent, unpleasant odour. It is produced primarily by the burning of fuels domestically and in industry, and secondarily by vehicles. Exposure to SO2 in ambient air has been associated with reduced lung function and an increased incidence of respiratory diseases, amongst others.


TABLE 4.2: SULPHUR DIOXIDE CONCENTRATIONS AND NO. OF EXCEEDANCES

ANNUAL AVERAGE (ppb)

10-MINUTE

EXCEEDANCES

24-HOUR EXCEEDANCES

SITE

2005 2004 2005 2004 2005 2004

Prospecton 6.7 7.2 0 0 0 0 Southern Works 16.2 22.2 240 796 14 34 Settlers 11.4 13.0 170 149 8 7 Ganges 10.0 12.4 0 5 0 2 Grosvenor 5.1 7.5 3 4 0 0 Wentworth 12.2 16.3 48 58 2 7 Jacobs (Balfour) 10.5 13.7 6 2 0 5 Ferndale 1.8 3.2 0 0 0 0 TOTAL 467 1014 24 55

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The SO2 annual averages measured at the various stations is presented in Table 4.2. The notable trend at all stations is a decrease in levels from 2004 to 2005. Particularly notable is the decrease of 6 ppb at Southern Works. This is primarily attributable to the commissioning of the SO2 scrubber at Mondi in May 05. This single initiative was responsible for the largest annual reduction in SO2 emissions in the eThekwini Municipality. Although retaining its status as the hot spot station, Southern Works has nevertheless made the transition to achieving compliance with respect to the annual limit value of 19 ppb. The 2005 SO2 annual average of 16.2 ppb at Southern Works is expected to reduce even further in 2006 as the scrubber would have been in operation for the full calendar year. Wentworth, which was previously highlighted as a station of concern, experienced a reduction in annual average from 16.3 ppb in 2004 to 12.2 ppb in 2005. This trend needs to continue in coming years to serve as evidence of improving air quality in the area. The low value of 1.8 ppb measured at Ferndale is indicative of the absence of large scale industrial activity in the northern areas of the municipality. During 2005, Southern Works recorded the highest number of daily exceedances of 14. However this is a reduction when compared to the 34 that were recorded for 2004. Similarly, the station experienced a reduction in 10-minute exceedances from 796 in 2004 to 250 in 2005. This again represents a substantial improvement in the air quality for the consecutive years in question. This is in contrast to Settlers, where the number of daily and 10-minute exceedances increased from 2004 to 2005. Several of these exceedances were attributable to process upsets at the Engen refinery in 2005. In addition to Southern Works and Settlers, the other stations where 10-minute exceedances occurred were Grosvenor, Wentworth and Jacobs. Wentworth was the only other station where a daily exceedance occurred. The overall picture with respect to SO2 exceedances looks positive, with a 54% total reduction in the number of 10-minute exceedances and a 56% total reduction in the number of daily exceedances from 2004 to 2005.

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FIGURE 4.1: SULPHUR DIOXIDE MONTHLY AVERAGES

0.0

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Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05 Sep-05 Oct-05 Nov-05 Dec-05

SO2 c

once

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Southern Works Settlers Grosvenor Wentworth Jacobs

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Prospecton Ganges Ferndale

Figure 4.1 contains the monthly SO2 trends, which generally depict increasing SO2 concentrations during winter months and decreasing concentrations during summer months. This is indicative of the greater prevalence of stable conditions during the winter months when inversion layers extend well into the day. The one notable exception to this trend was Southern Works, when the highest SO2 monthly average was recorded in January. Mondi’s installation of the SO2 scrubber in May 05 resulted in the reduced monthly averages in subsequent months. To further illustrate the point, the SO2 monthly average for September 04 at Southern Works was 35 ppb. This compares with the average of 13 ppb recorded for the same period in 2005, thus representing a drastic reduction.


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FIGURE 4.2 – SULPHUR DIOXIDE DIURNAL TRENDS

0.02.0

4.06.08.0

10.012.014.0

16.018.0

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Time of Day

SO2 c

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(ppb

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Prospecton Ganges Ferndale

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Southern Works Settlers Wentworth Jacobs Grosvenor

Figure 4.2 plots the SO2 diurnal trends for the various stations for 2005. The highest concentrations are recorded between 07:00 and 10:00. These drop in the afternoons and rise again in the evenings. The high morning concentrations are most likely due to the inversion layer dropping to its lowest level. This is followed by a break-up of the inversion layer, which results in a rapid drop in SO2 concentrations. The high SO2 concentrations at the Ganges, City Hall and Warwick in the morning could also be due to the increased traffic levels during peak time.

4.2 PARTICULATE MATTER

Table 4.3 contains the relevant PM10 data for 2005. The stations selected to measure PM10 include two traffic stations (Ganges and City Hall), one industrial station (Wentworth) and two background stations (King Edward and Ferndale). The annual limit value for PM10 as set out in SANS 1929 is 40 µg/m3.


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TABLE 4.3: PARTICULATE MATTER CONCENTRATIONS AND NO. OF EXCEEDANCES

ANNUAL AVERAGE (µg/m3)

24-HOUR EXCEEDANCES

STATION

2005 2004 2005 2004 Wentworth 37.9 39.1 24 27 Ganges 43.1 46.4 32 36 City Hall 37.7 38.1 17 21 King Edward 36.9 37.6 22 21 Ferndale 32.9 39.7 8 18 TOTAL 103 123

Ganges recorded the highest annual average, and it is the only station that exceeded the annual limit value. Although there is a noticeable reduction when compared to 2004, this traffic site has again exceeded the annual limit. This confirms that traffic in South Durban has a greater impact on PM10 levels than industrial activity, be it by a relatively small margin. The annual exceedance at Ganges is a source of concern as this represents a negative impact on the surrounding residential areas that are densely populated and on the school pupils and teachers of the Ganges Secondary School. The annual average of 37.9 µg/m3 at Wentworth provides a measure of the impact of industries on PM10 levels. The Wentworth station is impacted by the refineries, Mondi, industries in Jacobs, and Tongaat Huletts to a lesser extent. Although not an exceedance, the value of 37.9 µg/m3 is nevertheless high and needs to be closely monitored in future. The annual average at King Edward and Ferndale are considered to be too high as these stations represent industrial background and background respectively. A study undertaken by the Pollution Control Support Section resulted in the recommendation that the TEOM at King Edward must be moved to Southern Works and a sequential sampler then be installed at King Edward. The TEOM at Southern Works will serve to identify the industrial contribution to PM10.

All stations experienced several 24-hour exceedances of the 75 µg/m3 daily limit value. Although there was a reduction in the number of 24-hour exceedances at Ganges in 2005 when compared to the number in 2004, the station once again recorded the highest number of exceedances (32). The number of 24-hour exceedances is considered too high and will result in the health and well being of human beings being compromised. The monitoring has highlighted PM10 as a problem pollutant in Durban and will require a more concerted effort to address in future. Figure 4.16 reflects the directions of sources impacting Ganges.

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10 C

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Wentworth Ganges King Edward Ferndale City Hall

FIGURE 4.3 – PM10 MONTHLY AVERAGES

The monthly trends for PM10, as shown in Figure 4.3 are similar to those of SO2 in that increasing concentrations are obtained during the winter months and decreasing concentrations in the summer months. For PM10 however, the differences in concentrations between summer and winter months appear to be more pronounced.

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Ganges King Edward Wentworth City Hall Ferndale

FIGURE 4.4 – PARTICULATE MATTER DIURNAL TREND The PM10 diurnal trends of Figure 4.4 reveal that the highest concentrations are recorded in the mornings between 07:00 and 10:00. This is due to the combined effects of higher traffic volumes in the mornings and the prevalence of inversion layers.


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4.3 OXIDES OF NITROGEN

Nitrogen dioxide is a highly toxic, reddish brown gas that is created primarily from fuel combustion in industrial sources and vehicles. It creates an odorous haze that causes eye and sinus irritation, blocks natural sunlight and reduces visibility. It can severely irritate respiratory illnesses. Nitrogen dioxide contributes to the creation of acid rain and adversely impacts forests and other ecosystems. The importance of monitoring nitrogen dioxide is in helping to understand its influence in the formation of ozone and fine particles. Nitrogen dioxide is continuously monitored at eight stations. Each station represents impacts from different sources, namely, traffic, industry, residential and background.


1-HOUR EXCEEDANCES STATION

2005 2004 2005 2004 Southern Works 10.3 15.0 0 6 Ganges 21.0 22.0 4 9 King Edward 17.4 19.4 5 9 Warwick 21.0 23.8 1 3 Wentworth 12.1 12.9 4 3 City Hall 18.9 20.0 0 6 Jacobs 17.6 18.4 3 4 Ferndale 8.6 12.7 1 0 TOTAL 18 40

TABLE 4.4: NITROGEN DIOXIDE CONCENTRATIONS AND NO. OF EXCEEDANCES Table 4.4 presents the number of 1-hour exceedances as well as the annual averages for 2005 and 2004. All stations, with the exception of City Hall and Southern Works, recorded exceedances of the 1-hour limit value in 2005. However, it must be noted that there was an overall decrease in the number of exceedances from 40 in 2004 to 18 in 2005. The reason for this is not clear at this stage, but this trend needs to be monitored in future years. Two stations, Warwick and Ganges, jointly recorded the highest annual average of 21.0 ppb. This was followed by City Hall, thus confirming that traffic is the major contributor to NO2 emissions.

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FIGURE 4.5: NITROGEN DIOXIDE MONTHLY AVERAGES

0.05.0

10.015.020.025.030.035.040.0


NO

2 con

cent

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n (p

pb)

Ganges Warwick City Hall Ferndale

0.05.0

10.015.020.025.030.035.040.0


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2 con

cent

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n (p

pb)

Southern Works Wentworth King Edward Jacobs

Figure 4.5 presents the monthly averages of nitrogen dioxide. The lack of data at Warwick for January resulted from problems with the analyser and the data being invalidated. Missing data at Southern Works for April and May was as a result of problems with the analyser. Figure 4.5 depicts a general trend towards increasing concentrations in the winter months. As with SO2, this is linked to the prevalence of stable conditions during the winter months.


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FIGURE 4.6: NITROGEN DIOXIDE DIURNAL TRENDS

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Southern Works King Edw ard Wentw orth Jacobs

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Ganges Warwick City Hall Ferndale

Figure 4.6 represents the diurnal trend which shows an increase in concentrations in the morning and a decrease after midday, followed by an increase again in the afternoons. This corresponds with traffic volumes during the morning and afternoon peak hours. Also clear is the very high nitrogen dioxide concentrations at the traffic stations compared with the industrial stations. This implies that the major source of nitrogen dioxide is traffic.

4.4. OZONE

Ground level ozone is formed in air by the photochemical reaction of sunlight, nitrogen oxides (NOx), and a variety of volatile organic compounds (VOC). Ozone is measured because it is a precursor of volatile organic compounds, and it has a negative effect on the respiratory systems of human beings. Continuous measurements of ozone are performed at two stations, an industrial station (Wentworth) and a background station (Alverstone). Ozone is classified as a priority pollutant. Ozone limit values are thus contained in SANS 1929. However, these are reported as 1-hour (102 ppb) and 8-hour (61 ppb) limit values, in the absence of annual limit values.


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TABLE 4.5: OZONE CONCENTRATIONS AND NO. OF EXCEEDANCES


1-HOUR EXCEEDANCES

8-HOUR EXCEEDANCES STATION

2005 2004 2005 2004 2005 2004 Alverstone 25.6 23.7 1 0 11 2 Wentworth 14.7 14.8 0 3 0 2 TOTAL 1 3 11 4

An analysis of the results in Table 4.5 reveals that there was a drastic increase in the number of 8-hour exceedances in Alverstone in 2005 when compared 2004. There were no exceedances at Wentworth.

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Wentworth Alverstone Warwick

FIGURE 4.7: OZONE MONTHLY AVERAGES The monthly averages, as depicted in Figure 4.7, does not provide any discernable trends. At Alverstone, the highest monthly average of 34 ppb was recorded in August, a winter month. This is consistent with expected behaviour. However, the decrease in concentrations in the subsequent summer months was not substantial. The monthly averages for Wentworth displayed a trend that appears odd and inconsistent with expected behaviour. Missing data for June and July for Wentworth was due to that fact that the analyser was moved to Warwick for three months and then returned to Wentworth in August 05. A low average of approximately 8 ppb was obtained in August 05, when the highest levels are normally expected.

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0.05.0

10.015.020.025.030.035.040.045.050.0

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Wentworth Alverstone

FIGURE 4.8: OZONE DIURNAL TRENDS Figure 4.8 represents the diurnal trend which shows an increase in concentrations from 08:00 and 19:00. Lower concentrations were recorded early in the morning and late at night.

4.5 CARBON MONOXIDE (CO)

1-HOUR MAX (ppm)

8-HOUR MAX (ppm)

ANNUAL AVERAGE

(ppb)

1-HOUR EXCEEDANCES

8-HOUR EXCEEDANCES

STATION

2005 2004 2005 2004 2005 2004 2005 2004 2005 2004

Warwick 27.5 17.8 15.0 6.9 2.3 1.7 3 0 7 0 TABLE 4.6: CARBON MONOXIDE CONCENTRATIONS AND NO. OF EXCEEDANCES Currently, no annual limit value for CO concentration exists, as is evident in Table 4.1. However, presenting the measured values will serve useful in tracking yearly trends. CO is a traffic pollutant and as such is only measured at the Warwick traffic station, which is located at curb side in the Warwick Avenue Triangle.

The maximum 1-hour and 8-hour values were reported to be 27.5ppm and 15.0ppm, respectively for year 2005. These values were reportedly higher when compared to 2004, which were 17.8 ppm and 6.9 ppm respectively. These values violated the SANS 1929 CO limit values for the corresponding time periods. It must be noted that all three 1-hour exceedances occurred in the winter month of July at 08:00. This can be attributed to the high peak hour traffic and poor dispersion conditions during winter. Noted also is a 35.3% increase in the annual average in 2005 as compared to the annual average in 2004.


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0.00.51.01.52.02.53.03.54.04.55.0

Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05

CO c

once

ntra

tion

(ppb

)

Warw ick

FIGURE 4.9: CARBON MONOXIDE MONTHLY AVERAGES The CO averages for the period April to November show a distinct seasonal trend, with maximum concentrations being recorded during mid winter to autumn (June to August), which are associated with poor dispersion conditions.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Time of Day

CO

con

cent

ratio

n (p

pb)

Warwick

FIGURE 4.10: CARBON MONOXIDE DIURNAL TRENDS Figure 4.10 reflects the diurnal CO concentration trend. As anticipated the CO concentration are at a peak in the early hours of the morning between 05:00 and 10:00 and later in the day between 15:00 and 20:00. It’s also noted that the 2005 maximum CO concentrations attained during those peak hours are significantly higher compared to year 2004. This is associated with higher traffic volumes and poor dispersion conditions during these periods.

4.6. TOTAL REDUCED SULPHUR (TRS)

Total reduced sulphur (TRS) is not classified as a criteria pollutant, and was thus not considered in the DEAT standard setting process. The European Union has however prescribed an odour threshold of 4.8 ppb for hydrogen sulphide. The odour threshold for


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TRS was derived from this value. A study undertaken by the Pollution Control Support Unit revealed that hydrogen sulphide constitutes 60% of TRS. Based on this information, it was then determined that the odour threshold for TRS is 7.8 ppb.


TABLE 4.7: TRS CONCENTRATIONS AND NO. OF EXCEEDANCES


30-MIN EXCEEDANCES

STATION 2005 2004 2005 2004 Southern Works 3.6 4.1 2141 859 Settlers 2.9 2.2 257 141 TOTAL 2398 1000

From Table 4.7, it is evident that Southern Works is the TRS hotspot, having recorded 2141 30-minute exceedances, more than double the number recorded in 2004. There was also a significant increase in the number of 30-minute exceedances (257) at Settlers when compared to 141 exceedances in 2004. The extent of the problem has necessitated closer interaction with the major TRS polluters Southern Waste Water Treatment Works and Mondi.

0.0

1.0

2.0

3.0

4.0

5.0

6.0


TRS

con

cent

ratio

n (p

pb)

Southern Works Settlers

FIGURE 4.11: TOTAL REDUCED SULPHUR MONTHLY AVERAGES

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Time of Day

TRS

con

cent

ratio

n (p

pb)

Southern Works Settlers

FIGURE 4.12: TOTAL REDUCED SULPHUR DIURNAL TRENDS

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The diurnal trend shows that the higher levels of TRS occurred during the early hours of the mornings and late hours of the day, and during low wind speeds. This indicates that the higher levels originate from low sources and that meteorology plays a key role. When refinery flaring occurs, higher levels of TRS are often noted. The higher TRS value at Southern Works with respect to Settlers is most likely an indication that the Southern Works station is located closer to sources. The sewage treatment plant at Southern Works is a source of sulphur based compounds like hydrogen sulphide. Another source is Mondi Paper Mill, which is also located close to the monitoring station and also releases similar compounds.

4.7 METEOROLOGICAL RESULTS

Meteorology plays a crucial role in air pollution as it greatly influences the transport and dispersion of air pollutants. There are currently six meteorological stations that form part of the continuous monitoring network. Details of these stations and the various parameters that they measure are listed in Table 2.2. Also listed is the percent of valid data recorded during the past year. Data recovery was acceptable at all stations except for Wentworth. The loss of wind direction data at Wentworth was due to various problems, the most significant one being the damage caused to communication cards by lightning.

4.7.1 Wind Roses

A wind rose is a quantitative graphical summary of the wind direction and speed for a given time. It also displays the frequency of the wind direction at each of the 12 major compass points and the average wind speed in each direction (wind direction refers to the direction from which the wind is blowing). The seasons for wind roses are classified as follows:

SEASON PERIOD Summer December 2004 – February 2005 Autumn March 2005 - May 2005 Winter June 2005 – August 2005 Spring September 2005 – November 2005

TABLE 4.8: CATEGORIES OF SEASONS

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FIGURE 4.13: SEASONAL WIND ROSES AT SOUTHERN WORKS

Figure 4.13 presents the seasonal wind roses for Southern Works. The summer wind rose indicates that the most frequent wind direction is from the north-easterly direction at a frequency of 25.9 %, with a secondary maximum from the south-westerly direction at a frequency of 17.3 %. The mean wind speeds for the observations among all sectors range from 0.4 to 8 m/s. The strongest winds are from the north-easterly and south-easterly directions at 8 m/s and above. The weakest winds occur from north-westerly direction at 1.1 to 2 m/s. Calm conditions (<0.4 m/s) during this period constituted 0.9 % of the total observations. The autumn wind rose indicates that the most frequent wind direction is from north-east at a frequency of 23.3 %, followed by north-west at a frequency of 12.1%. Mean wind speeds for the observations among all sectors range from 0.4 to 8 m/s. The strongest winds are from the north-east, south and south-west at 8 m/s. The weakest winds resulting from calm conditions during this period constituted 3 % of the total observations.


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The winter wind rose indicates that the most frequent wind direction is from north-east at a frequency of 16.1%, followed by south-west at a frequency of 12.4%. The mean wind speeds for the observations amongst all sectors range from 0.4 to 8 m/s. The strongest winds are from the north-east and south-east sector at 8 m/s and above. The weakest winds occur from northwest between 1.1m/s and 2 m/s. Calm conditions during this period constituted 4.3% of the total observations. The spring wind rose indicates that the most frequent wind direction is from north-east at a frequency of 26%, followed by south-west at a frequency of 21.2 %. The mean wind speeds for the observations amongst all sectors range from 0.4 to 8 m/s. The strongest winds are from the north-east and south-east at 8m/s and higher. The weakest winds occur from northwest at 1.1 to 2 m/s. Calm conditions during this period constituted 1.2 % of the total observations. Calm winds have a wind speed of < 0.4 m/s and are usually associated with inversion conditions which result in poor dispersion of pollutants.

4.7.2 Stability Frequency

Atmospheric stability is the measure of resistance to further dilution and dispersion of pollutants.

FIGURE 4.14: DIURNAL DISTRIBUTION OF STABILITY CLASSES

Figure 4.14 shows the stability frequency distribution for Southern Works for 2005. The average stability for the year 2005 shows that in most cases light stable and stable conditions occurred more than 60% of the time.


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Annual Probability Distribution of Stability Classes by time of day

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Time of day

% O

ccur

renc

e du

ring

each

hou

Unstable Neutral Light Stable Stable

FIGURE 4.15: PROBABILITY DISTRIBUTION OF STABILITY CLASSES BY TIME OF DAY

Figure 4.15 shows the diurnal distribution of stability classes. The time period between 18:00 and 08:00 is dominated by light stable followed by stable conditions. There are occurrences of neutral conditions. For the time period between 09:00 and 17:00 stability frequencies fluctuate between neutral and unstable conditions. There are occurrences of light stable and a few very stable conditions during this time.

4.7.3 Pollution Roses

Pollution roses provide a useful illustration of pollution concentrations as a function of wind direction. Pollution roses can be easily interpreted and serve as a useful tool in source apportionment studies. The construction of pollution roses is based on measured data.


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FIGURE 4.16: ANNUAL SO2 POLLUTION ROSE AT SOUTHERN WORKS AND SETTLERS Figure 4.16 contains the annual SO2 pollution roses for Southern Works and Settlers. An analysis of the roses indicates that the maximum frequency of SO2 concentrations occurred in the south-westerly direction between the 195o- 225o wind vector at a concentration of 39.5 ppb. This range in directions aligns most closely to all Sapref’s stacks and four of Mondi’s stacks. This was followed by a concentration of 21.4 ppb in the 235o- 255o wind vector. There is also a source in the north-easterly (45o- 75o) wind vector that contributed to 16 ppb. The pollution rose diagram drawn for Settlers indicates that the maximum frequency of SO2 dispersion occurred along the north-easterly wind direction (45o-75o) with a maximum concentration of 14.3 ppb followed by 13.6 ppb at 15o- 45o wind vector. The second highest concentration is aligned with all Engen’s stacks. There is also a source in the southerly (165o

-195o) wind direction that contributed to 12.9 ppb.


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FIGURE 4.17: ANNUAL SO2 POLLUTION ROSE AT WENTWORTH

The pollution rose for Wentworth indicates that the maximum frequency of SO2 dispersion occurred along the south westerly direction (195o- 225o) with a maximum concentration of 23.6 ppb. The sources aligned with the maximum concentration are Engen, Sapref and Mondi. This is followed by 22 ppb between 285o-315o wind direction and 21.5 ppb at north-westerly 265o- 285o wind direction. The most likely source for this contribution is area sources in the Jacobs area.


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FIGURE 4.18: ANNUAL PM10 POLLUTION ROSE AT GANGES The Ganges station recorded 32 exceedances of the annual PM10 limit value. Its annual pollution rose is presented above in Figure 4.18. The important derivation from the pollution rose is that PM10 is a regional source and not attributable to distinct point sources. The highest concentrations were recorded from the north-westerly directions. Lying in this direction are major traffic hotspots like Edwin Swales Drive and South Coast Road, and the Mobeni industrial area.


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5. CONCLUSIONS AND RECOMMENDATIONS a. The network achieved an overall data capture rate of 90% for pollutant data and 93.3% for

meteorological data for 2005. This compares favourably with the target of 90 %. However it must be noted that there was a 3.3 % decrease in the data capture for pollutant data for 2005 when compared to 2004. This can be attributed to technical problems experienced with some of the analyers and the lightning strikes that affected the stations.

b. The results of the quarterly calibration audits revealed that several SO2 and NOx analysers

experienced excessive span drifts that were beyond the limits of acceptability. This resulted in the invalidation of data recorded during the periods of high drift. The overall performances of analysers had improved with time.

c. Southern Works recorded the highest annual average for SO2 (16.2 ppb), which is below the

limit value (19 ppb). This reflected a significant decrease in the SO2 value as compared to the annual average of 22.2 ppb for 2004. The SO2 levels at Wentworth (12.2ppb) have also decreased as compared to an annual average of 16.3 ppb for 2004. These stations will continue to be closely monitored.

d. The total of 2141 exceedances of the TRS odour threshold at Southern Works versus the 257

for Settlers confirms Southern Works as the TRS hotspot in South Durban. Furthermore, the results of specialist studies showed that the Southern Waste Water Treatment Works and Mondi were the major sources of TRS in Merebank. These sources are currently in the process of implementing H2S reduction programmes.

e. The major source of SO2 and TRS pollution in South Durban is industry and the waste water

treatment works. f. Ganges was the only station that recorded the highest an annual average for PM10 (43.1

µg/m3) and exceeded the annual limit value (40 µg/m3). The other traffic stations also recorded annual averages that were close to the limit value, though not exceeding it. There are marginal decreases as compared to the values in 2004.

g. The Warwick, Ganges and City Hall stations recorded the highest annual averages for NO2

of 21.0 ppb, 21.0 ppb and 18.9 ppb, respectively. These stations are all representative of vehicular traffic.

h. The major source of PM10 and NO2 pollution in South Durban is traffic. i. The high PM10 annual average recorded at King Edward of 36.9 µg/m3 is an indication that

the station is not suitably located to serve as a background station. The location of the station needs to be re-assessed.

j. The dominant wind directions are from the north-easterly and south-westerly directions as

reflected in the seasonal wind roses. k. Pollution roses indicate that the highest SO2 concentrations measured at Southern Works

was from the direction of Mondi. Similarly, the highest SO2 concentrations measured at Settlers was from the direction of Engen.

l. An analysis of the PM10 pollution rose at Ganges revealed that the traffic hotspots were the

major contributors to high levels recorded at the Ganges station.

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APPENDIX 1 CALIBRATION AUDIT RESULTS SULPHUR DIOXIDE

DATE STATION COMP AUDIT ZERO (PPB)

RESPONSE (PPB)

AUDIT SPAN

RESPONSE % DRIFT

SPAN ACTION

2/02/2005 Prospecton SO2 0.0 1.0 679 675 -0.6 OK 11/05/2005 Prospecton SO2 0.0 1.0 926.3 858.6 -7.3 OK 27/07/2005 Prospecton SO2 0.0 0.0 800.8 219 -72.7 L 25/10/2005 Prospecton SO2 0.0 -2.0 645.2 714.9 10.7 OK 31/01/2005 Southern Works SO2 0.0 0.0 679 842 24.0 H 10/05/2005 Southern Works SO2 0.0 0.0 926.3 1063 14.7 OK 25/07/2005 Southern Works SO2 0.0 0.0 800.8 708 -11.6 OK 24/10/2005 Southern Works SO2 0.0 0.0 926 932 0.6 OK 3/02/2005 Settlers SO2 0.0 45.0 679 755 11.2 OK 12/05/2005 Settlers SO2 0.0 -2.9 940.5 994 5.6 OK 27/07/2005 Settlers SO2 0.0 0.0 800.8 547 -31.7 L 27/10/2005 Settlers SO2 0.0 3.0 940.5 910 -3.2 OK 01/02/2005 Ganges SO2 0.0 0.0 679.0 687 1.2 OK 11/05/2005 Ganges SO2 0.0 2.0 940.5 882 -6.2 OK 26/07/2005 Ganges SO2 0.0 -1.0 940.5 894 -4.9 OK 25/10/2005 Ganges SO2 0.0 0.0 940.5 886 -5.8 OK 02/02/2005 Grosvenor SO2 0.0 0.0 679.0 735 8.2 OK 12/05/2005 Grosvenor SO2 0.0 -3.0 800.8 983 22.7 H 27/07/2005 Grosvenor SO2 0.0 -2.0 985.1 745 -24.3 L 25/10/2005 Grosvenor SO2 0.0 -1.0 800.8 1028 28.4 H 31/01/2005 Jacobs SO2 0.0 0.0 679.0 539 -20.6 L 10/05/2005 Jacobs SO2 0.0 -4.0 800.8 1321 65.0 H 27/07/2005 Jacobs SO2 0.0 0.0 985.1 652 -33.8 L 25/10/2005 Jacobs SO2 0.0 0.0 998.5 1206 20.8 H 31/01/2005 Wentworth SO2 0.0 0.0 679.0 693 2.1 OK 10/05/2005 Wentworth SO2 0.0 0.0 940.5 906 -3.7 OK 25/07/2005 Wentworth SO2 0.0 1.0 940.5 970 3.1 OK 24/10/2005 Wentworth SO2 0.0 0.0 940.5 998 6.1 OK 2/02/2005 Ferndale SO2 0.0 0.0 679.0 694 2.2 OK 12/05/2005 Ferndale SO2 0.0 0.0 926.3 749 -19.1 L 28/07/2005 Ferndale SO2 0.0 0.0 800.8 903 12.8 OK 27/10/2005 Ferndale SO2 0.0 1.0 645.2 624 -3.3 OK

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NITROGEN OXIDE


RESPONSE (PPB)

AUDIT SPAN

RESPONSE % DRIFT

SPAN ACTION

01/02/2005 Southern Works NO 0.0 0.0 477.3 432 -9.5 OK 26/07/2005 Southern Works NO 0.0 -1.0 841 345 -59.0 L 24/10/2005 Southern Works NO 0.0 1.0 847.2 826 -2.5 OK 01/02/2005 Ganges NO 0.0 0.0 515.5 491.0 -4.7 OK 11/05/2005 Ganges NO 0.0 0.0 772.5 820.0 6.1 OK 26/07/2005 Ganges NO 0.0 0.0 849.6 774 -8.9 OK 26/10/2005 Ganges NO 0.0 0.0 8499.6 1031 21.3 H 03/02/2005 King Edward NO 0.0 0.0 477.3 429.1 -10.1 OK 13/05/2005 King Edward NO 0.0 0.0 727.9 604.0 -17.0 L 28/07/2005 King Edward NO 0.0 0.0 827.3 1039 25.6 H 27/102005 King Edward NO 0.0 0.0 841.6 838 -0.4 OK 01/02/2005 Warwick NO 0.0 0.0 484.4 418 -13.7 OK 11/05/2005 Warwick NO 0.0 -2.0 790.1 863 9.2 OK 26/07/2005 Warwick NO 0.0 -1.0 827.3 674 -18.5 L 25/10/2005 Warwick NO 0.0 1.0 841.6 1073 27.5 H 03/02/2005 City Hall NO 0.0 1.0 530.9 494 -7.0 OK 11/05/2005 City Hall NO 0.0 0.0 727.9 768 5.5 OK 28/07/2005 City Hall NO 0.0 -1.0 827.3 762 -7.9 OK 26/10/2005 City Hall NO 0.0 0.0 576.3 696 20.8 H 10/05/2005 Jacobs NO 0.0 0.0 790.1 363 -54.1 L 25/07/2005 Jacobs NO 0.0 -1.0 827.3 525 -36.5 L 24/10/2005 Jacobs NO 0.0 -1.0 841.6 1463 73.8 H 31/01/2005 Wentworth NO 0.0 1.0 459.2 540 17.6 H 10/05/2005 Wentworth NO 0.0 2.0 772.5 1186 53.5 H 25/07/2005 Wentworth NO 0.0 1.0 849.6 260 -69.4 L 24/10/2005 Wentworth NO 0.0 2.0 849.6 1313 54.5 H 2/02/2005 Ferndale NO 0.0 0.0 459.3 282.7 -38.4 L 12/05/2005 Ferndale NO 0.0 0.1 727.9 665.7 -8.5 OK 28/07/2005 Ferndale NO 0.0 -0.4 841.6 1442 71.3 H 27/10/2005 Ferndale NO 0.0 0.0 576.3 477.3 -17.2 L

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CARBON MONOXIDE


RESPONSE (PPB)

AUDIT SPAN

RESPONSE % DRIFT

SPAN ACTION

01/02/2005 Warwick CO 0.0 0.2 8.6 8.3 -3.3 OK HYDROGEN SULPHIDE


RESPONSE (PPB)

AUDIT SPAN

RESPONSE % DRIFT

SPAN ACTION

03/02/2005 Settlers H2S 0.0 18.3 551.8 598.0 8.4 OK 27/10/2005 Settlers H2S 0.0 1.0 901.0 1012 12.3 OK 31/01/2005 Southern Works H2S 0.0 0.6 551 674 22.1 H 10/05/2005 Southern Works H2S 0.0 -8.4 901 1209 34.2 H 26/07/2005 Southern Works H2S 0.0 1.0 901 1012 12.3 OK 27/10/2005 Southern Works H2S 0.0 8.0 901 981 8.9 OK OZONE


RESPONSE (PPB)

AUDIT SPAN

RESPONSE % DRIFT

SPAN ACTION

2/02/2005 Alverstone O3 0.0 0.0 500 523 4.6 OK 25/05/2005 Alverstone O3 0.0 1.0 500 549 9.6 OK 26/07/2005 Alverstone O3 0.0 -2.0 500 467 -6.6 OK 26/10/2005 Alverstone O3 0.0 5.0 500 532 6.4 OK 31/01/2005 Wentworth O3 0.0 2.0 500 504 0.8 OK 11/05/2005 Warwick O3 0.0 1.0 500 540 8.0 OK 29/07/2005 Wentworth O3 0.0 3.0 500 443 -11.4 OK 25/10/2005 Wentworth O3 0.0 1.0 500 504 0.8 OK

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APPENDIX 2

DIRECTIONS OF POINT SOURCES FROM MONITORING STATIONS

STACK NAME SOUTHERN WORKS WENTWORTH SETTLERS Engen 20-Sulphur 3 Stack 49 200 18 Engen 10-Sulphur 2 Stack 48 200 17 Engen 9-Asphalt Stack 45 201 17 Engen 7-SAFOR Stack 77 197 29 Engen 8-SCPX Stack 50 198 22 Engen 5-Combo Stack 47 196 23 Engen 3-Combo Stack 46 194 25 Engen 2-NCPX Stack 50 187 31 Engen 1-NCPX Stack 47 188 29 12-New Crude Furnace 47 183 30 Sapref VBR Stack 201 206 214 Sapref FCCU Stack 198 205 214 Sapref Plat Stack 195 204 213 Sapref Lubes Stack 188 204 213 Sapref Utility Stack 198 205 212 Sapref CDU 2 Stack 201 206 216 Mondi Boiler 8 Stack 216 211 250 Mondi Boiler 6 Stack 225 213 254 Mondi Boiler 5 Stack 227 213 255 Mondi Boiler 2 Stack 214 211 249 Mondi Boiler 1/4 Stack 217 212 251 Tongaat Hulett Coal Boiler Stack 4 340 359

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APPENDIX 3 A. STATION DESCRIPTIONS

FIGURE 2.1 – LOCATIONS OF AIR MONITORING AND METEOROLOGICAL STATIONS The locations of the air monitoring and meteorological stations that constitute the network are depicted in Figure 2.1.


Page 31 of 36

a) PROSPECTON

The station is located at 1 Prospecton Place, Prospecton, on the roof of the Department of Labour building, alongside the N2 Freeway, southbound. The station is at an elevation of 24 m above sea level. Its location represents the furthermost southerly point of the air quality monitoring network. It serves as an industrial background station and measures the pollutant levels entering the basin from the Prospecton/Umbogintwini area. The single pollutant measured at the station is sulphur dioxide.

b) SOUTHERN WORKS

The station is located at 2 Bayfield Road, Merebank, within the Southern Sewage Works site. The residential areas of Merebank and Wentworth are relatively close by. The station is at an elevation of 13 m above sea level. The representativity of the station is urban industrial. It is alternately a hot spot station as its location represents the area of highest pollutant concentrations in South Durban. It has been specifically located to distinguish the emissions from Sapref and Mondi. Measured at the station are a range of pollutants including SO2, NO/NO2/NOx and TRS. The meteorological parameters measured at the station are wind speed, wind direction, ambient temperature, delta temperature, net radiation and barometric pressure. These are used for the purposes of dispersion modelling and source apportionment studies.


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c) SETTLERS

This station is located Settlers School, 98 Lakhimpur Road, Merebank, on the valley floor and represents an urban industrial environment. The elevation of the stations is 23 m above sea level. It was selected to record concentrations from stack emissions and ground level emissions from Engen and Mondi. It also represents concentrations within immediate residential area of Merebank. The pollutant parameters measured at the station are SO2 and TRS.

d) GANGES

The Ganges station is located in the grounds of the Ganges Secondary School, Jammu Road, Merebank, along the Southern Freeway, northbound. The elevation of the station is 20 m above sea level. The station is representative of a suburban traffic zone. The station location was selected to obtain information on the levels of NO2 and PM10 from traffic and SO2 from the medium and small scale industries in the Merebank, Mobeni and Jacobs areas.


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e) GROSVENOR

This station is located in the grounds of the Grosvener Girls High School, 20 Bideford Road, Bluff, and is representative of a residential area. The station was selected to measure the level of pollution the community is likely to be exposed to. The elevation of the station is 23 m above sea level. The single pollutant measured at the station is SO2, the major source of which is industries in the area. The meteorological station measures wind speed, wind direction, ambient temperature and precipitation (rain).

f) KING EDWARD

The station is located at the King Edward Hospital, Sydney Road, Congella, adjacent to the Medical Centre, at an elevation of 23 m above sea level. It is representative of an urban background and the measurements recorded here would indicate the type and levels of pollutants that could enter the valley. The pollutant parameters measured here are NO/NO2/NOx and PM10. A bubbler was recently installed to measure SO2 over 3 to 4 day averaging periods.


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g) WARWICK

The Warwick station is located within the perimeter of the Thekwini Business Centre, 27 Alice Steet, at an elevation of 3 m above sea level. It is representative of urban traffic and the site was primarily selected to measure traffic pollutants, NO/NO2/NOx and CO. The Warwick Avenue station represents a high intensity traffic zone. Thus, a possible shortcoming of the station is a lack of PM10 measurements.

h) WENTWORTH

The Wentworth station is located at the Wentworth Reservoir, Boston Road, near the Wentworth Hospital. Its elevation above sea level is 78 m and it is representative of a residential environment. The major impacts that the stations quantifies are those related to industrial pollution from Merbank, Jacobs, Mobeni and Clairwood. This is an existing site from the old network that has been upgraded with new equipment and a new meteorological tower. The parameters measured at the station are SO2, NO/NO2/NOx, PM10, O3, wind speed, wind direction, ambient temperature, delta temperature and barometric pressure.


Page 35 of 36

i) CITY HALL

The station is located in the City Hall parking area at an elevation of 5m above sea level. It represents urban traffic and was selected to quantify traffic pollutants in the CBD. The pollutants measured at the station are NO/NO2/NOx and PM10. The measurement of SO2 at the station was terminated after it was found that SO2 levels were relatively low and there was a greater need to measure TRS at Southern Works with the analyser.

j) JACOBS MET

This is a meteorological station, at an elevation of 38m above sea level, located at Divfood, Richard Carter Road, Jacobs. The site was selected to be representative of emissions from the small and medium-sized industries in the Jacobs area. The meteorological parameters measured at the station are wind speed and wind direction. This data forms an important input in dispersion models.

k) ALVERSTONE


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The Alverstone station is located at the Roseway Waldorf School in Alverstone, at an elevation of 823m above sea level. The representivity of the station is that of urban background. It was selected to ascertain the pollutant type and load present in background areas that may impact on the South Durban basin. The only parameter currently being measured at the station is ozone, although the measurement of SO2 and PM10 will commence in the not too distant future.

l) JACOBS

The Jacobs station is located at the SAP vehicle depot in Balfour Road, Jacobs at an elevation of 16 m above sea level. It is an industrial background station and was selected to be representative of emissions from the small and medium-sized industries in the Jacobs area. The parameters measured at the station are SO2 and NO/NO2/NOx.

a) SAPREF

The Sapref station is located at the Sapref Oil Refinery at an elevation of 7 m above sea level. The station serves solely as a metrological station and the data generated by the station is used for modelling purposes. The parameters measured at the station are wind speed and wind direction.

n) HARBOUR

The Harbour meteorological station is located at Pier 2, off Langeberg Road, in Maydon Wharf. The station elevation is 5 m above sea level. It was designed to measure wind speed, wind direction, ambient temperature and rain.


Page 37 of 36


APPENDIX 4

INSTRUMENTATION

a) SO2 FLOURESCENT ANALYSER

Continuous SO2 measurements were performed at eight stations during 2005. The SO2 analyser at Settlers doubles as an H2S analyser. Due to the need for H2S data to resolve complaints in the Merebank vicinity, the City Hall SO2 analyser was moved to Southern Works to measure H2S.

Of the nine SO2 analysers, eight are Monitor Lab and one is API. The Monitor Lab 9850B series were acquired in 2003 and used for the full monitoring period under review. An older API Model 110A analyser was incorporated into the new network from the Settlers caravan. All the analysers are designated under USEPA regulations as equivalent method EQSA-0193-092. The analysers have been set to operate in a 0 to 1 000 ppb range and are ultraviolet fluorescence spectrometers.

b) NO2 CHEMILUMINESCENT ANALYSER

Continuous NO2 measurements were performed at eight stations during 2005. The analysers use gas-phase chemilluminescence detection to perform continuous analyses of nitrogen oxide (NO), total oxides of nitrogen (NOx) and nitrogen dioxide (NO2). The instrument functions by measuring NO and NOx, and calculates NO2 as the difference between the former two. All NO2 analysers were supplied by Monitor Europe, with model ML 9841 B having been the preferred choice. The analysers have been set to operate in a 0 to 1 000 ppb range and are designated under USEPA regulations as an equivalent method.

c) O3 ULTRAVIOLET ANALYSER

O3 measurements were performed at three stations during 2005. The analysers are non-dispersive ultraviolet photometers that measure ozone by determining the amount of UV absorbed by the sample. The analysers were supplied by Monitor Europe, with the model ML 9811 having been the preferred choice. The analysers operate in a 0 to 1 000 ppb range and have been designated under USEPA regulations as equivalent method EQOA-0193-091.

d) PM10 TEOM ANALYSER

Continuous PM10 measurements were performed at five stations during 2005. The analysers utilise the TEOM (tapered element oscillating microbalance) mass measurement system for measurement of particulate matter. The analysers were acquired from Rupprecht & Patashnick, with the series 1400a being the model of choice. The analysers operate in a 0 to 1 000 µg/m3 range. The USEPA has designated the TEOM 1400a as an equivalent method for the determination of PM10 concentrations.

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e) CO ANALYSER

CO was continuously measured at the Warwick station during 2005. The detection and measurement of CO is based on the absorption of infra red (IR) radiation by CO molecules at wavelengths near 4.7 microns.

The analyser is an old API Model 300 CO analyser that was previously used in the Settlers Caravan. The range of measurement of the analyser is 1 to 1 000 ppm, with a lower detection limit of < 0.05 ppm.

f) AUTOMATIC WEATHER STATIONS

The six weather stations continuously measure a range of meteorological parameters. A single RM Young Model 27005 gill UVW anemometer at Southern Works measures the three orthogonal vectors of the wind. The other five stations are equipped with R M Young Model 05103 wind monitors that measure horizontal wind speed and direction. The monitors measure in the 0 to 30 m/s range of wind speeds. Ambient temperature is measured continuously at five stations with the aid of RM Young Model 41372VC/VF relative humidity/temperature probes. In addition, relative humidity is measured at Grosvenor with the same instrument. The measuring ranges are -10 oC to 60 oC for temperature, and 0 to 100 % for relative humidity.

Net radiation is measured continuously at the Harbour with the aid of an RM Young Model 43408 gill aspirated radiation shield.

g) DATA ACQUISITION

Data acquisition is achieved with a software based system called Envidas. The version in use is EnvidasFW (Envidas for Windows). The Envidas programme was sourced from Envitech in Israel. The software is run on non-proprietary desktops based at the monitoring stations and supports up to eight RS232 (digital) channels. Air quality and meteorological data at the stations are logged by Envidas. A central server located at eThekwini Health is used to poll the data from the monitoring stations. The data is then stored in an SQL data base.

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Air Pollution and GIS