29 Estimating Respirable Dust Exposure from Inhalable Dust Exposure

Abstract

Abstract From the exposition database ‘MEGA’, established by the Institute for Occupational Safety and Health of the German Social Accident Insurance, measurements of inhalable dust (n=103 825) and respirable dust (n=222 501) were selected to create conversion functions of inhalable to respirable dust concentrations in different workplaces. These functions are important for exposure assessment or retrospective evaluations of exposure situations and for epidemiologic studies, when just one fraction was analyzed. For the determination of the conversion functions, 15 120 pairs of inhalable and respirable dust, which were measured in parallel, were formed. The assignment was done considering various variables such as sampling date and time or workplaces. The measured values were log-transformed and a linear regression analysis was done, calculating a conversion function for the whole dataset with an adjusted R2 > 0.580 and R>0.760. On the basis of technical information, the dataset was divided into different dust groups considering material and working activities as relevant variables, resulting in six working activity, three material, four working activity-material combination and eleven heuristic groups. For each of these groups a conversion function was calculated as well and will be described in the presentation. The models admissibility was evaluated by examining the assumptions of linear regression such as no autocorrelation, normal distribution of residuals and variance homogeneity. On the basis of that, future measurements in different workplaces and the dust exposure can easier be evaluated, when measurements of just one fractions were made and the other can be estimated using the conversion functions.