Estimate of Premature Deaths Associated with Fine Particle Pollution (PM2.5) in California Using a U.S. Environmental Protection Agency Methodology

California Air Resources Board
http://www.arb.ca.gov/research/health/pm-mort/pm-report_2010.pdf

[Executive Summary] The United States Environmental Protection Agency’s (U.S. EPA) recently released “Quantitative Health Risk Assessment for Particulate Matter”  provides national estimates of premature mortality associated with fine particulate matter pollution (PM2.5), supported by its finding that the scientific evidence shows a causal connection between mortality and exposure to PM2.5. This report describes the U.S. EPA’s risk assessment methodology for calculating premature mortality, and its 2009 Integrated Science Assessment for particulate matter that provides the underlying scientific basis for the calculations. These U.S. EPA reports were prepared as part of U.S. EPA’s periodic review of the National Ambient Air Quality Standards (NAAQS) for particulate matter. The U.S. EPA risk assessment estimated premature deaths associated with PM2.5 nationwide, and in 15 urban areas including Los Angeles and Fresno. This report applies the U.S. EPA methodology to California on a statewide basis.

The U.S. EPA’s reports were peer reviewed in a public process by the Clean Air Scientific Advisory Committee (CASAC) Particulate Matter Review Panel, an independent peer review body of national scientists. The methodology described in this report is used to quantify the premature deaths associated with current levels of PM2.5 in California, and to estimate the premature deaths avoided by achieving compliance with the current annual air quality standard for PM2.5. This report also describes the method used by U.S. EPA to calculate the health benefits of PM2.5 emission reductions from specific source categories.

The foundation of the methodology is the association between long-term PM2.5 concentrations and premature death, which is provided by peer reviewed health studies. There are a large number of published health studies that estimate the additional risk of mortality due to long-term exposure to PM2.5. U.S. EPA’s new quantitative health risk assessment for particulate matter uses a 2009 study (Krewski et al., 2009) for the core analysis. This study is an extension of a 2002 study (Pope et al., 2002) used in the previous PM2.5 NAAQS risk assessment. This report estimates premature death from PM2.5 in California based on the 2009 Krewski study.

Using U.S. EPA’s methodology, the estimated number of annual PM2.5-related premature deaths in California is 9,200 with an uncertainty range of 7,300–11,000. This estimate of premature deaths is based on the latest exposure period in the 2009 Krewski study with data from 116 U.S. cities and about 500,000 people.

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