Assessing Diesel Particulate Matter Exposure by a Multi-Metric Approach in Three Different Workplaces in Quebec (Canada)

摘要

Elemental carbon and total carbon are the surrogates usually used to assess diesel particulate matter (DPM) exposure, but the measurement of different indicators by direct-reading instruments (DRI) is also described and includes advantages and limitations. The aim of this study was to assess and compare several indicators of DPM exposure in three workplaces by using a multi-metric approach. Three workplaces in Quebec (Canada) were evaluated: An underground mine (Wl; n=12), a subway tunnel (W2; n=12) and a truck repair workshop (W3; n=12). Ambient particle number concentration (PNC), submicron particulate matter (PM1), and submicron elemental carbon (EC1-DRI) were measured by DRI. Filter-based samples (FBS) were also collected to estimate the respirable and submicron fractions of elemental carbon (ECR and EC1-FBS), as well as the respirable and submicron fractions of total carbon (TCR and TC1). The geometric means of the DRI were: 128,000; 32,800 and 22,700 particles/cm3 for PNC in W1, W2 and W3, respectively; 165, 20.4 and 6.9 μg/m3 for PM1; and 148, 25 and 4.1 μg/m3 for EC1-DRI. W1 also had the highest concentrations of ECR, EC1-FBS, TCR and TC1. EC1-DRI showed the strongest association with EC1-FBS when considering all workplaces (ρ= 0.966; p<0.001), but this association decreased at lower concentrations of DPM. PM1 (ρ= 0.936; p<0.001) and PNC (ρ= 0.871; p<0.001) also showed a strong positive correlation with EC1-FBS. Ratios of 1.05, 1.76 and 1.30 were calculated between TC1/PM1 for W1, W2 and W3, respectively. This study provided solid information about the concentrations, as well as their associations, of several indicators of DPM exposure in three different exposure contexts.