Personal exposure of Paris office workers to nitrogen dioxide and fine particles

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Abstract
Aims: (1) To obtain an overall estimate of variability of personal exposure of Paris office workers to fine particles (PM2.5) and nitrogen dioxide (NO2), and to quantify their microenvironmental determinants. (2) To examine the role of potential determinants of indoor concentrations. Methods: Sixty two office workers in a Paris municipal administration (all non-smokers) were equipped with personal samplers: passive samplers for 48 hours for NO2 (n = 62), and active pumps for 24 hours for PM2.5 (n = 55). Simultaneous measurements were performed in homes and offices; the local air monitoring network provided ambient concentrations. A time activity diary was used to weight measured concentrations by time spent in each microenvironment in order to estimate exposure concentrations. Results: On average, PM2.5 personal exposure (30.4 μg/m3) was higher than corresponding in-home (24.7 μg/m3) and ambient concentrations (16.7 μg/m3). Personal exposure to NO2 (43.6 μg/m3) was significantly higher than in-home concentrations (35.1 μg/m3) but lower than the background outdoor level (60.1 μg/m3). Personal exposures to PM2.5 and NO2 were not significantly different from in-office concentrations. PM2.5 and NO2 personal exposures were not significantly correlated. In-home, in-office, in-transit, outdoor time weighted concentrations, and time spent in other indoor microenvironments explain respectively 86% and 78% of personal variations in PM2.5 and NO2. In-home PM2.5 concentration was primarily influenced by exposure to environmental tobacco smoke, and secondly by the ambient level (R2 = 0.20). NO2 in-home concentration was affected mostly by the ambient level and gas cooking time (R2 = 0.14). Conclusion: While results show the major contribution of in-home and in-office concentrations to both NO2 and PM2.5 personal exposures, the identification of indoor level determinants was not very conclusive.