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Exposure Modeling of Residential Infiltration of Black Carbon for NEXUS Participants
Citation:
Breen, M., J. Burke, S. Batterman, C. Croghan, AND V. Isakov. Exposure Modeling of Residential Infiltration of Black Carbon for NEXUS Participants. ISES Annual Meeting, Henderson, NV, Henderson, NV, October 18 - 23, 2015.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using outdoor concentrations. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improve exposure estimates in health studies. A critical aspect of EMI is estimation of air exchange rates (AER) and indoor infiltration of outdoor (ambient) air pollutants for individual homes where people spend most of their time. The AER, defined as the airflow into and out of buildings, can impact indoor air pollutant concentrations and resulting occupant exposures. Our goal was to evaluate and apply a mechanistic AER model linked with a dynamic mass balance infiltration model for black carbon (BC) to predict residential AER, BC infiltrations, and ambient BC indoor concentrations for the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS). The NEXUS is examining traffic-related air pollution exposures and respiratory effects in asthmatic children living near major roads in Detroit, Michigan. Cross validation was used with a subset of NEXUS homes with measurements of daily AER (24 h average) and continuous indoor and outdoor BC concentrations (5 min average) on five consecutive days during fall 2010 and spring 2011. The models were then applied to predict hourly BC indoor concentrations for all homes (N=213) during the three year study (2010 - 2012) using hourly outdoor concentrations predicted for each home. Results show considerable house-to-house (spatial) and temporal variations in residential AER and BC infiltrations. Using this novel approach, NEXUS will be one of the firsthealth studies to apply a calibrated and home-specific dynamic mass balance infiltration model for BC, and to include the spatial and temporal variations of BC indoor concentrations for over 200 individual homes across multiple years into an exposure assessment in support of improving risk estimates.
