Personal Exposures to PM2.5 by Microenvironment among Residents of California’s Central Valley
JESSICA TRYNER, Xiaoying Li, Luis Hernandez Ramirez, Bonnie Young, Sherry WeMott, Mollie Phillips, Grant Erlandson, Celine Campos, Daniel Dean, Nayamin Martinez, John Volckens, Sheryl Magzamen, Colorado State University
Abstract Number: 324
Working Group: Aerosol Exposure
Abstract
People are exposed to particulate matter (PM) air pollution in varied environments, including at home, at work, and in transit. As a result, a person’s exposure to PM often differs from the local outdoor concentration. We measured personal and in-home PM concentrations for 149 participants from 88 households across urban and rural communities in California's Central Valley. We used wearable monitors to collect 24-h time-integrated filter samples, time-resolved optical sensor data on PM concentration, and time-resolved GPS data to investigate spatiotemporal variations in personal exposure to PM2.5. We clustered GPS coordinates using machine learning to identify key locations where participants spent time and were exposed to PM2.5. Daily average personal exposures tended to exceed outdoor concentrations (median personal = 15.7 µg m-3; median personal - outdoor difference = 5.8 µg m-3). Personal exposures to PM2.5 were better correlated with in-home concentrations than with outdoor concentrations (Spearman correlation = 0.63 versus 0.24). Most participants (59%; "Group 1") spent > 80% of their time indoors at home, where they received a proportional amount of PM2.5 exposure. Some participants (28%; "Group 2") received a disproportionately large amount of PM2.5 exposure in their homes despite spending less time there. A smaller proportion (13%; “Group 3”) spent ≤ 80% of their time indoors at home and received a disproportionate amount of PM2.5 exposure elsewhere. Among Group 3 participants, the non-home environments associated with the largest fractions of exposure were agriculture and transit. Participants in Group 3 were more likely to work outside the home (80% in Group 3 versus 37% in Group 1) and were more likely to work in agriculture (83% of employed participants in Group 3 versus 50% in Groups 1 and 2), thus highlighting the relevance of occupational exposure to PM in this study population.