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Abstract
This paper describes an operational evaluation of the US Environmental Protection Agency’s (EPA) Air Pollution Exposure Model (APEX). APEX simulations for a multipollutant ambient air mixture, i.e. ozone (O3), carbon monoxide (CO), and particulate matter 2.5 microns in diameter or less (PM2.5), were performed for two seasons in three study areas in central Los Angeles. APEX predicted microenvironmental concentrations were compared with concentrations of these three pollutants monitored in the Exposure Classification Project (ECP) study during the same periods. The ECP was designed expressly for evaluating exposure models and measured concentrations inside and outside 40 microenvironments. This evaluation study identifies important uncertainties in APEX inputs and model predictions useful for guiding further exposure model input data and algorithm development efforts. This paper also presents summaries of the concentrations in the different microenvironments.
Public Interest Statement
Decades of research and numerous studies have consistently indicated air pollution contributes to sickness, disease development, and premature death. To best understand the relationship between air pollution and the negative impacts to human health, it is crucial to account for how people might come in contact with pollutants and experience the important features of exposure, such as the magnitude, duration, frequency, and pattern of pollutant concentrations that occur in their immediate surroundings. In this study, we use a novel multipollutant exposure modeling approach that combines the complexities of human behavior with air pollutant concentrations that vary across an urban area considering movement across space, time, and interaction within built-environments. While reasonable agreement was observed between model estimations and measured concentrations, the most significant uncertainties are identified to further enhance the benefits associated with using a model based approach to estimate multipollutant exposures.
Competing interests
The authors declare no competing interest
Additional information
Notes on contributors
Ted R. Johnson
Ted R. Johnson is the President and Research Director of TRJ Environmental, Inc., a consulting company specializing in analysis of air quality data and estimation of population exposure. He has designed exposure models used by the US EPA to simulate the exposure of urban populations to air pollution.
John E. Langstaff
John E. Langstaff and Dr Stephen Graham are exposure modelers at the US EPA. Their research encompasses the development and application of exposure modeling techniques.
Stephen Graham
John E. Langstaff and Dr Stephen Graham are exposure modelers at the US EPA. Their research encompasses the development and application of exposure modeling techniques.
Eric M. Fujita
Dr Eric M. Fujita, emeritus research professor at the Desert Research Institute (DRI), was the Principal Investigator for the ECP sampling and analysis project. His research interests included chemical characterization of emission sources and measurement and characterization of exposures to toxic air contaminants.
David E. Campbell
David E. Campbell is an associate research scientist at DRI, whose research interests include characterization and apportionment of gaseous and aerosol pollutants from mobile sources, and the influence of mobile source contributions on photochemical processes.
