Personal exposure to PM2.5 in different microenvironments and activities for retired adults in two megacities, China

Abstract

Microenvironmental concentrations and time-activity patterns influence personal exposure to fine particulate matter (PM2.5). However, the variations and contributions of PM2.5 exposures from various microenvironments (MEs) and activities remain unclear. In this study, gravimetrically corrected real-time personal PM2.5 measurements were collected during routine activities in different MEs from 66 non-smoking retired adults. Exposure data were collected for five consecutive days over two seasons in Nanjing (NJ) and Beijing (BJ), China. Measured PM2.5 concentrations varied substantially both between and within different MEs and activities. The highest average concentrations were observed in restaurants (NJ: mean 192 μg/m3, SD 242 μg/m3; BJ: mean 91 μg/m3, SD 79 μg/m3) and were associated with sources such as passive smoking and cooking emissions. Overall, PM2.5 concentrations in different MEs and activities were moderately to highly correlated with outdoor PM2.5 concentrations (Spearman's r = 0.51-0.97) except in restaurants and during passive smoking. The at-home ME contributed approximately 85 % of the total PM2.5 exposure, corresponding to the participants spending about 87 % of their time there. The majority of household exposures occurred during sleeping, cooking, and other home-based activities. Transportation accounted for <5 % of total exposure. Our results indicate that improving indoor air quality, especially residential indoors, is important to reduce personal exposure to PM2.5.