Semi-empirical model for the aspiration efficiencies of personal aerosol samplers of the type widely used in occupational hygiene

This paper extends what it known about the aspiration efficiencies of blunt aerosol samplers at large angles and under Orientation-averaged' conditions to the important case of personal samplers worn by workers. Attention is focused on three sampling devices which have particular relevance to industrial hygiene sampling in Britain, the United States and elsewhere. A semi-empirical model for aspiration efficiency is described, based on physical considerations of the nature of air and particle motion near an asymmetric sampling system, like that relevant to personal sampling. The resultant model contains a number of coefficients which are fitted by non-linear regression to experimental data sets which were available from previously published experiments for the three samplers in question. Agreement for all three data sets is good, with an overall R_corr². of 68%. Such semi-empirical models can be useful for predicting and interpreting sampler performance until practical versions of more rigorous mathematical and numerical models become available.