Estimating exposure to traffic-related PM2.5 for women commuters using vehicle and personal monitoring

Abstract

Exposure to traffic-related fine particulate matter air pollution (tr-PM2.5) has been associated with adverse health outcomes including preterm birth and low birthweight. In-vehicle exposure to tr-PM2.5 can contribute substantially to total tr-PM2.5 exposure. Because average commuting habits of women differ from men, a research gap is estimating in-vehicle tr-PM2.5 exposures for women commuters. For 46 women commuters in the Washington, D.C. metro area, we measured personal exposure to PM2.5 during all vehicle trips taken in a 48-h sampling period. We also measured 48-h integrated PM2.5 chemical constituents including black carbon and zinc. We identified trip times using vehicle monitors, specifically on-board diagnostics data loggers and dashboard cameras. For 386 trips, we estimated associations between PM2.5 exposure and trip characteristics using linear mixed models accounting for participant, day, and time of day. Additionally, we estimated associations between rush hour trip PM2.5 and 48-h integrated PM2.5 chemical constituents using linear models. Exposure to PM2.5 during trips was 1.9 μg/m3 (95% confidence interval (CI): 0.9, 2.9) higher than non-trip exposures and rush hour trip exposures were 3.2 μg/m3 (95% CI: 1.8, 4.6) higher than non-trip exposures on average. We did not find differences in PM2.5 exposure by trip length. Although concentrations of tr-PM2.5 chemical constituents were generally positively associated with rush hour trip PM2.5, associations were weak indicating that other settings contribute to total tr-PM2.5 exposure. Our study demonstrates the utility of combining vehicle monitors and personal PM2.5 monitors for estimating personal exposure to tr-PM2.5. Future work will investigate whether additional data collected by vehicle monitors, such as traffic and speed, can be leveraged to better understand tr-PM2.5 exposure among commuters.