EAS Inc. Technical Reports (no charge)
Hewett, P. (2005): Technical Report 05–01 - A Conceptual Model for Generating
Random Exposures for Use in Computer Simulations. Exposure Assessment Solutions,
Inc. (www.oesh.com).
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ABSTRACT
Computer simulation is usually the only means for predicting the ability of
a corporate sampling strategy to detect a poorly controlled work environment.
To date, several papers have been published that use computer simulation to
evaluate particular sampling strategies, but information on how to generate
random exposures from a hypothetical exposure group is not readily available.
A conceptual model is presented that can be applied to either conventional,
single-shift TWA exposure limits (LTWA) or the less common
long-term average exposure limits (LLTA). Using this
model, procedures for generating random exposure values are presented.
In addition, equations are derived from the model for calculating the 95th percentile
“worker 95th percentile exposure” and the 95th percentile “worker
mean exposure”. These equations can easily be modified to calculate other
percentiles. Equations are also presented for calculating the fraction of workers
(qP) expected to have an individual
95th percentile exposure greater than the LTWA, and the
fraction of workers (qM) expected
to have an individual mean exposure greater than the LLTA.
Such calculations can be used in an educational setting to estimate and visualize
(via graphs) the distributions of worker 95th percentiles and worker mean exposures.
In summary, the model presented can be used to (a) design exposure assessment
strategies through computer simulation, and (b) train industrial hygienists.
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