| California Wildfires of 2008: Coarse and Fine Particulate Matter Toxicity Teresa C. Wegesser,1 Kent E. Pinkerton,2 and Jerold A. Last1 1Department of Pulmonary and Critical Care Medicine, and 2Department of Pediatrics, School of Medicine, University of California, Davis, California, USA Abstract
Background: During the last week of June 2008, central and northern California experienced thousands of forest and brush fires, giving rise to a week of severe fire-related particulate air pollution throughout the region. California experienced PM10‒2.5 (particulate matter with mass median aerodynamic diameter > 2.5 µm to < 10 µm ; coarse ) and PM2.5 (particulate matter with mass median aerodynamic diameter < 2.5 µm ; fine) concentrations greatly in excess of the air quality standards and among the highest values reported at these stations since data have been collected. Objectives: These observations prompt a number of questions about the health impact of exposure to elevated levels of PM10‒2.5 and PM2.5 and about the specific toxicity of PM arising from wildfires in this region. Methods: Toxicity of PM10‒2.5 and PM2.5 obtained during the time of peak concentrations of smoke in the air was determined with a mouse bioassay and compared with PM samples collected under normal conditions from the region during the month of June 2007. Results: Concentrations of PM were not only higher during the wildfire episodes, but the PM was much more toxic to the lung on an equal weight basis than was PM collected from normal ambient air in the region. Toxicity was manifested as increased neutrophils and protein in lung lavage and by histologic indicators of increased cell influx and edema in the lung. Conclusions: We conclude that the wildfire PM contains chemical components toxic to the lung, especially to alveolar macrophages, and they are more toxic to the lung than equal doses of PM collected from ambient air from the same region during a comparable season. Key words: air pollution, alveolar macrophage, lung inflammation, mouse, PM2.5, PM10, source-specific particulate matter. Environ Health Perspect 117:893–897 (2009) . doi:10.1289/ehp.0800166 available via http://dx.doi.org/ [Online 2 February 2009]
Address correspondence to J.A. Last, CCRBM, 6519 Genome and Basic Science Building, 451 Health Sciences Dr., Davis, CA 95616 USA. Telephone: (530) 752-6230. Fax: (530) 752-8632. E-mail: jalast@ucdavis.edu We thank F. Mitloehner, S. Cliff, N. Kado, and D. Bennett for their assistance with access to the sampling site and PM sampling. This study was funded in part by ES-07059 from the National Institute of Environmental Health Sciences, U07/CCU906162 from the National Institute for Occupational Safety and Health, and RD-83241401 from the U.S. Environmental Protection Agency. The authors declare they have no competing financial interests. Received 8 September 2008 ; accepted 2 February 2009.
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