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www.arbounie.nl
Exposure to solvents in the metal fabrication
and engineering industry
2nd European Conference on AWARE and other coding
systems, Gent, October 4 & 5, 2007
Henri Heussen, PhD, &
Hester Dekker, MSc
Background
1. Web based tool metal sector: coating & degreasing
2. Aim: exposure to solvents self risk assessment by SME’s and larger companies
Tool: two validated routes
Good Practices (Risk Management Measures = RMM) Model: Occupational Air Requirement (OAR) or Required Air Quantity
(RAQ)
This part: validation of good practices and applied ventilation modelNext part IVAM: using the same exposure data > validation of AWARE
ventilation model
Activities studied
Good Practices
Degreasing by dipping – (semi) closed system
Mixing paint – closed mixer
Cleaning spray guns – closed washing machine with LEV
Model
Brushing/rolling
Spraying
Model: calculation OAR
n
i i
iii
OEL
fVOAR
1
1000
Legenda:
OAR: Occupational Air Requirement (m3/l)
Vi: Volume solvent/liter paint (ml/l)
i: index including all solvents in the paint
ρi: specific gravity (g/ml)
fi: evaporation factor (default 1)
OELi: Occupational Exposure Limit solvent (mg/m3)
or hardener & thinner
or hardener & thinner
Calulation needed ventilation
QOAR: Ventilation needed according to OAR (m3/hr)
OAR: Occupational Air Requirement (m3/l)
Ve: Amount used (l)
T: Time (hr)
T
VeOARQOAR
Calculation Exposure Index (EI)
Legenda:
EImodel: Exposure index
QOAR: Needed ventilation (m3/hr)
Qd: Actual ventilation (m3/hr)
d
OARmodel Q
QEI
Conclusions Good Practices:
Predefined Good Practices are indeed good (statistically validated)
Also other Good Practices found (some statistically validated)
Detailed description of Good Practice is necessary and a prerequisite for correct use of the tool
Results brushing/rolling(excluding natural ventilation) 7 companies
20 measurem.
y = 0,66x + 0,12R2 = 0,71
0,0
1,0
2,0
3,0
4,0
0,0 1,0 2,0 3,0 4,0
BI gemeten
BI
mo
delE
I mo
del
EI measurements
Results spraying(excluding natural ventilation) 6 companies
14 measurem.
y = 0,98x + 0,36R2 = 0,88
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0
BI gemeten
BI
mo
delE
I mo
del
EI measurements
Conclusions model
Very good correlation between model and measurement data
However, model does not always overestimate
Therefore for brushing/rolling a safety factor is needed!
For spraying not a priori necessary > political decision
To be calculated on the basis of sensitivity/specificity
Conclusions model (continued)
After adding safey factor(s) model = validated exposure
assessment tool
Erring to the side of caution: separation between local and general ventilation MSDS upper limit range (volume solvent/l) more than one sprayer in the same room > total amount of
solvents used by all sprayers attributed to one sprayer
Covers a wide range: in amount of paint used per time room volume type of ventilation ventilation capacity measured exposure index