Fine Particulate Matter National Ambient Air Quality Standards: Public Health Impact on Populations in the Northeastern United States

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In this article we identify the magnitude of general and susceptible populations within the northeastern United States that would benefit from compliance with alternative U.S. Environmental Protection Agency (EPA) annual and 24-hr mass-based standards for particulate matter (PM) with an aerodynamic diameter [less than or equal to] 2.5 [micro]m (P[M.sub.2.5]). Understanding the scale of susceptibility in relation to the stringency or protectiveness of PM standards is important to achieving the public health protection required by the Clean Air Act of 1970. Evaluative tools are therefore necessary to place into regulatory context available health and monitoring data appropriate to the current review of the PM National Ambient Air Quality Standards (NAAQS). Within the New England, New Jersey, and New York study area, 38% of the total population are < 18 or [greater than or equal to] 65 years of age, 4-18% of adults have cardiopulmonary or diabetes health conditions, 12-15% of children have respiratory allergies or lifetime asthma, and 72% of all persons (across child, adult, and elderly age groups) live in densely populated urban areas with elevated P[M.sub.2.5] concentrations likely creating heightened exposure scenarios. The analysis combined a number of data sets to show that compliance with a range of alternative annual and 24-hr P[M.sub.2.5] standard groupings would affect a large fraction of the total population in the Northeast. This work finds that current P[M.sub.2.5] standards in the eight-state study area affect only 16% of the general population, who live in counties that do not meet the existing annual/24-hr standard of 15/65 [micro]g/[m.sup.3]. More protective P[M.sub.2.5] standards recommended or enacted by California and Canada would protect 84-100% of the Northeast population. Standards falling within current ranges recommended by the U.S. EPA would protect 29-100% of the Northeast population. These considerations suggest that the size of general and susceptible populations affected by the stringency of alternative PM standards has broad implications for risk management and direct bearing on the U.S. EPA's current NAAQS review and implementation. Key words: air pollution, National Ambient Air Quality Standards, northeastern United States, particulate matter, P[M.sub.2.5], populations, public health, sensitive, susceptible. doi:10.1289/ehp.7822 available via http://dx.doi.org/[Online 10 May 2005]

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Exposure to ambient fine particulate matter [particulate matter (PM) with an aerodynamic diameter [less than or equal to] 2.5 [micro]m (P[M.sub.2.5])] has been associated with a wide range of PM-related human health effects in general populations, including the aggravation of heart and lung disease and premature mortality (Brook et al. 2004; Holgate et al. 1999; Samet et al. 2000). The Clean Air Act of 1970 (CAA 1970) mandates the U.S. Environmental Protection Agency (EPA) to set health-based National Ambient Air Quality Standards (NAAQS) for certain pollutants known to be hazardous to human health, including PM. NAAQS provisions require the U.S. EPA to establish standards requisite to protect public health with an adequate margin of safety at a level that avoids unacceptable risks. Legislative history has interpreted the PM NAAQS margin of safety provision as requiring the protection of both general populations and sensitive subpopulations, or those subgroups potentially at increased risk for ambient particle health effects (National Air Quality Standards Act of 1970). Accordingly, the PM NAAQS--which are currently under review by the U.S. EPA--are intended to protect the health of the most sensitive members of society as well as the general population.

During the last decade, regulatory agencies have increasingly recognized that persons sensitive or susceptible to PM are more numerous and diverse than once thought. To achieve the public health protection called for by the CAA, the National Research Council (NRC) has recommended that subpopulations at increased risk from PM pollution should be identified and the nature and magnitude of their risk understood in the context of standard setting (NRC 2004). …