Academic journal article Environmental Health Perspectives

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A National Analysis

Academic journal article Environmental Health Perspectives

The Effect of Fine and Coarse Particulate Air Pollution on Mortality: A National Analysis

Article excerpt

BACKGROUND: Although many studies have examined the effects of air pollution on mortality, data limitations have resulted in fewer studies of both particulate matter with an aerodynamic diameter of [less than or equal to] 2.5 [micro]m ([PM.sub.2.5]; fine particles) and of coarse particles (particles with an aerodynamic diameter > 2.5 and < 10 [micro]m; PM coarse). We conducted a national, multicity time-series study of the acute effect of [PM.sub.2.5] and PM coarse on the increased risk of death for all causes, cardiovascular disease (CVD), myocardial infarction (MI), stroke, and respiratory mortality for the years 1999-2005.

METHOD: We applied a city- and season-specific Poisson regression in 112 U.S. cities to examine the association of mean (day of death and previous day) [PM.sub.2.5] and PM coarse with daily deaths. We combined the city-specific estimates using a random effects approach, in total, by season and by region.

RESULTS: We found a 0.98% increase [95% confidence interval (CI), 0.75-1.22] in total mortality, a 0.85% increase (95% CI, 0.46-1.24) in CVD, a 1.18% increase (95% CI, 0.48-1.89) in MI, a 1.78% increase (95% CI, 0.96-2.62) in stroke, and a 1.68% increase (95% CI, 1.04-2.33) in respiratory deaths for a 10-[micro]g/[m.sup.3] increase in 2-day averaged [PM.sub.2.5]. The effects were higher in spring. For PM coarse, we found significant but smaller increases for all causes analyzed.

CONCLUSIONS: We conclude that our analysis showed an increased risk of mortality for all and specific causes associated with [PM.sub.2.5], and the risks are higher than what was previously observed for [PM.sub.10]. In addition, coarse particles are also associated with more deaths.

KEY WORDS: cardiovascular diseases, fine particulate matter, mortality, PM coarse, respiratory disease, season, time series. Environ Health Perspect 117:898-903 (2009). doi:10.1289/ ehp.0800108 available via http://dx.doi.org/ [Online 13 February 2009]

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Many multicity studies have shown that ambient particulate air pollution, generally measured as particulate matter with aerodynamic diameter [less than or equal to] 10 [micro]m ([PM.sub.10]), is associated with increased risk of death for broadly defined cardiovascular or respiratory causes, using time series analysis (Dominici et al. 2000; Katsouyanni et al. 1997; Schwartz 1994, 2000) or case-crossover analysis (Schwartz 2004; Zeka et al. 2005).

It is generally thought that fine particles (those with an aerodynamic diameter of [less than or equal to]2.5 [micro]m; [PM.sub.2.5]) are more harmful to health than larger particles ([PM.sub.10]) (Cifuentes et al. 2000; Schwartz et al. 1996), although some studies have shown stronger effects with coarse particles (particles 2.5-10 [micro]m in aerodynamic diameter) (Ostro et al. 2000).

The literature on the association between fine particles ([PM.sub.2.5]) and mortality is relatively sparse, because of two main issues: The U.S. Environmental Protection Agency (EPA) began [PM.sub.2.5] monitoring in 1999, and mortality data from the National Center for Health Statistics (NCHS) were not available nationwide after the year 2000. Nevertheless, several multicity studies have been performed. Using early [PM.sub.2.5] monitoring data from the Harvard Six City Study, Schwartz et al. (1996) reported a strong association between 2-day average [PM.sub.2.5] and daily deaths, but little association with coarse particles. A study of eight Canadian cities similarly found associations with fine but not coarse particles (Burnett et al. 2000). Dominici et al. (2007) examined [PM.sub.2.5]-mortality associations using national data in the United States, but only for the years 1999-2000.

Franklin and co-authors in two papers (Franklin et al. 2007, 2008) addressed this issue a different way. They used mortality data up to year 2000 from the NCHS, whereas they obtained mortality data directly from state health departments for the years 2001-2005 to examine the mortality effects of [PM. …

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