Factors Affecting the Association between Ambient Concentrations and Personal Exposures to Particles and Gases

• Type of Material: Article
• Authors: Stefanie Ebelt Sarnat, Emory University; Brent A. Coull, Harvard School of Public Health; Joel Schwartz, Harvard School of Public Health; Diane R. Gold, Harvard School of Public Health; Helen H. Suh, Harvard School of Public Health
• Language: English
• Date: 2006-05
• Publisher: National Institute of Environmental Health Sciences (NIEHS)
• Publication Version: Final Published Version
• Copyright Statement: Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, "Reproduced with permission from Environmental Health Perspectives"); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
• Final Published Version (URL): http://ehp.niehs.nih.gov/
• Title of Journal or Parent Work: Environmental Health Perspectives
• ISSN: 0091-6765
• Volume: 114
• Issue: 5
• Start Page: 649
• End Page: 654
• Grant/Funding Information: Funding for this study was from the National Institute of Environmental Health Sciences (ES-09825), the U.S. Environmental Protection Agency (R826780-01-0, R827353-01-0), the Ohio Coal Development Office within the Ohio Air Quality Development Authority (CDO/D-98-2), the Electric Power Research Institute (EP-P4464/C2166), the American Petroleum Institute (78142), and the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (DE-FC26-00NT40771).
• Keywords: nitrogen dioxide; confounding; particle components; PM2.5; personal exposure; epidemiology; sulfur dioxide; ambient concentration; ozone; air pollution
• Research Categories: Health Sciences, Occupational Health and Safety; Health Sciences, Public Health

Abstract

Results from air pollution exposure assessment studies suggest that ambient fine particles [particulate matter with aerodynamic diameter ≤ 2.5 μg (PM2.5)], but not ambient gases, are strong proxies of corresponding personal exposures. For particles, the strength of the personal–ambient association can differ by particle component and level of home ventilation. For gases, however, such as ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), the impact of home ventilation on personal–ambient associations is untested. We measured 24-hr personal exposures and corresponding ambient concentrations to PM2.5, sulfate (SO42−), elemental carbon, O3, NO2, and SO2 for 10 nonsmoking older adults in Steubenville, Ohio. We found strong associations between ambient particle concentrations and corresponding personal exposures. In contrast, although significant, most associations between ambient gases and their corresponding exposures had low slopes and R2 values; the personal–ambient NO2 association in the fall season was moderate. For both particles and gases, personal–ambient associations were highest for individuals spending most of their time in high- compared with low-ventilated environments. Cross-pollutant models indicated that ambient particle concentrations were much better surrogates for exposure to particles than to gases. With the exception of ambient NO2 in the fall, which showed moderate associations with personal exposures, ambient gases were poor proxies for both gas and particle exposures. In combination, our results suggest that a) ventilation may be an important modifier of the magnitude of effect in time-series health studies, and b) results from time-series health studies based on 24-hr ambient concentrations are more readily interpretable for particles than for gases.