AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Multipollutant Analysis of Microenvironmental Exposures
KIRSTEN KOEHLER, Nicholas Good, Christian L'Orange, Anna Molter, Jennifer Peel, John Volckens, Johns Hopkins School of Public Health
Abstract Number: 569 Working Group: Aerosol Exposure
Abstract Air pollutant concentrations vary temporally and spatially and, as such, regional outdoor air monitors do a poor job of representing personal exposures indoors and outdoors. Because particles from different sources may have different toxicity in terms of human health, the ability to apportion human exposure to different sources of air pollutants is desired. The goal of this study was to assess variability of microenvironmental exposures in Fort Collins, Colorado, a typical small city. Participants of the Fort Collins Commuter Study were outfitted with a backpack containing direct-reading monitors to estimate concentrations of fine particulate matter (PM2.5 mass), PM2.5 black carbon, carbon monoxide and ultrafine particle number concentration for 24 hours. By pairing personal monitors with a GPS receiver, we are able to map exposures to microenvironment, sources and activities. Additionally, participants filled out daily surveys about building characteristics and exposure sources in different microenvironments.
We apportioned personal exposures from 44 participants on a total of 350 sampling days into five commonly visited microenvironments: home, work, transit, eatery and other. Exposures tended to be highest in transit and at eateries and lowest at work for all pollutants. An exposure amplification factor (EFa) was defined as the ratio of the fraction of 24-hour cumulative exposure apportioned to a given microenvironment divided by the fraction of time spent in that microenvironment. Transit and Eatery microenvironments tended to have values greater than one for black carbon, carbon monoxide, and particle number concentration exposures, indicating that although these microenvironments account for a relatively small fraction of time, they can be important to cumulative exposures. Additionally, models were developed to describe the distributions of personal exposures and the factors that contribute to within- and between- person variability. Ambient concentrations, geographic covariates, and ventilation characteristics were most predictive of personal exposures.