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BACKGROUND: Prospective cohort studies constitute the major source of evidence about the mortality effects of chronic exposure to particulate air pollution. Additional studies are needed to provide evidence on the health effects of chronic exposure to particulate matter ≤ 2.5 µm in aerodynamic diameter (PM2.5) because few studies have been carried out and the cohorts have not been representative. OBJECTIVES: This study was designed to estimate the relative risk of death associated with long-term exposure to PM2.5 by region and age groups in a U.S. population of elderly, for the period 2000--2005. METHODS: By linking PM2.5 monitoring data to the Medicare billing claims by ZIP code of residence of the enrollees, we have developed a new retrospective cohort study, the Medicare Cohort Air Pollution Study. The study population comprises 13.2 million participants living in 4,568 ZIP codes having centroids within 6 miles of a PM2.5 monitor. We estimated relative risks adjusted by socioeconomic status and smoking by fitting log-linear regression models. RESULTS: In the eastern and central regions, a 10-µg/m3 increase in 6-year average of PM2.5 is associated with 6.8% [95% confidence interval (CI), 4.9--8.7%] and 13.2% (95% CI, 9.5--16.9) increases in mortality, respectively. We found no evidence of an association in the western region or for persons ≥ 85 years of age. CONCLUSIONS: We established a cohort of Medicare participants for investigating air pollution and mortality on longer-term time frames. Chronic exposure to PM2.5 was associated with mortality in the eastern and central regions, but not in the western United States. [ABSTRACT FROM AUTHOR]

In this paper, we present national maps of relative rates of mortality associated with short-term exposure to particulate matter < 10 µm in aerodynamic diameter (PM[sub 10]). We report results for 88 of the largest metropolitan areas in the United States from 1987 to 1994 for all-cause mortality, combined cardiovascular and respiratory deaths, and other causes of mortality. Maximum likelihood estimates of the relative rate of mortality associated with PM[sub 10] and the degree of statistical uncertainty were obtained for each of the 88 cities by fitting a separate log-linear regression of the daily mortality rate on air pollution level and potential confounders. We obtained Bayesian estimates of the relative rates by fitting a hierarchical model that takes into account spatial correlation among the true city-specific relative rates. We found that daily variations of PM[sub 10] are positively associated with daily variations of mortality. In particular, the relative rate estimates of cardiovascular and respiratory mortality associated with PM[sub 10] are larger on average than the relative rate estimates of all-cause and other-cause mortality. The estimated increase in the relative rate of death from cardiovascular and respiratory mortality, all-cause mortality, and other-cause mortality were 0.31% (95% posterior interval, 0.15-0.5), 0.22% (95% posterior interval, 0.1-0.38), and 0.13% (95% posterior interval, -0.05 to 0.29), respectively. Bayesian estimates of the city-specific relative rates ranged from 0.23% to 0.35% for cardiovascular and respiratory mortality, from 0.18% to 0.27% for all causes, and from 0.10% to 0.20% for other causes of mortality. The spatial characterization of effects across cities offers the potential to identify factors that could influence the effect of PM[sub 10] on health, including particle characteristics, offering insights into mechanisms by which PM[sub 10] causes adverse health effects. [ABSTRACT FROM AUTHOR]

Presents letters to the editor, published in the November 2001 issue of the journal 'Environmental Health Perspectives,' on issues dealing with health. Confirmation of uterotrophic activity for 4-methylbenzylidine camphor in the immature rat; Impact of repeated exposure to fungi in a water-damaged building on the health of workers; Need of further research on markers of exposure to bioaerosols in case of patients with microbial exposure-related lung damage.

BACKGROUND: Population-based studies have estimated health risks of short-term exposure to fine particles using mass of PM2.5 (particulate matter ≤ 2.5 μm in aerodynamic diameter) as the indicator. Evidence regarding the toxicity of the chemical components of the PM2.5 mixture is limited. OBJECTIVE: In this study we investigated the association between hospital admission for cardiovascular disease (CVD) and respiratory disease and the chemical components of PM2.5 in the United States. METHODS: We used a national database comprising daily data for 2000-2006 on emergency hospital admissions for cardiovascular and respiratory outcomes, ambient levels of major PM2.5 chemical components [sulfate, nitrate, silicon, elemental carbon (EC), organic carbon matter (OCM), and sodium and ammonium ions], and weather. Using Bayesian hierarchical statistical models, we estimated the associations between daily levels of PM2.5 components and risk of hospital admissions in 119 U.S. urban communities for 12 million Medicare enrollees (≥ 65 years of age). RESULTS: In multiple-pollutant models that adjust for the levels of other pollutants, an interquartile range (IQR) increase in EC was associated with a 0.80% [95% posterior interval (PI), 0.34-1.27%] increase in risk of same-day cardiovascular admissions, and an IQR increase in OCM was associated with a 1.01% (95% PI, 0.04-1.98%) increase in risk of respiratory admissions on the same day. Other components were not associated with cardiovascular or respiratory hospital admissions in multiple-pollutant models. CONCLUSIONS: Ambient levels of EC and OCM, which are generated primarily from vehicle emissions, diesel, and wood burning, were associated with the largest risks of emergency hospitalization across the major chemical constituents of PM2.5. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although numerous studies have demonstrated links between particulate matter (PM) and adverse health effects, the chemical components of the PM mixture that cause injury are unknown. OBJECTIVES: This work characterizes spatial and temporal variability of PM2.5 (PM with aerodynamic diameter < 2.5 µm) components in the United States; our objective is to identify components for assessment in epidemiologic studies. METHODS: We constructed a database of 52 PM2.5 component concentrations for 187 U.S. counties for 2000-2005. First, we describe the challenges inherent to analysis of a national PM2.5 chemical composition database. Second, we identify components that contribute substantially to and/or co-vary with PM2.5 total mass. Third, we characterize the seasonal and regional variability of targeted components. RESULTS: Strong seasonal and geographic variations in PM2.5 chemical composition are identified. Only seven of the 52 components contributed ≥ 1% to total mass for yearly or seasonal averages [ammonium (NH4+), elemental carbon (EC), organic carbon matter (OCM), nitrate (NO3-), silicon, sodium (Na+), and sulfate (SO42-)]. Strongest correlations with PM2.5 total mass were with NH4+ (yearly), OCM (especially winter), NO3- (winter), and SO42- (yearly, spring, autumn, and summer), with particularly strong correlations for NH4+ and SO42- in summer. Components that co-varied with PM2.5 total mass, based on daily detrended data, were NH4+, SO42- , OCM, NO3-, bromine, and EC. CONCLUSIONS: The subset of identified PM2.5 components should be investigated further to determine whether their daily variation is associated with daily variation of health indicators, and whether their seasonal and regional patterns can explain the seasonal and regional heterogeneity in PM10 (PM with aerodynamic diameter < 10 µm) and PM2.5 health risks. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lack of knowledge regarding particulate matter (PM) characteristics associated with toxicity is a crucial research gap. Short-term effects of PM can vary by location, possibly reflecting regional differences in mixtures. A report by Lippmann et al. [Lippmann et al., Environ Health Perspect 114:1662-1669 (2006)] analyzed mortality effect estimates from the National Morbidity, Mortality, and Air Pollution Study (NMMAPS) for 1987-1994. They found that average concentrations of nickel or vanadium in PM2.5 (PM with aerodynamic diameter < 2.5 μm) positively modified the lag-1 day association between PM10 and all-cause mortality. OBJECTIVE: We reestimated the relationship between county-specific lag-1 PM10 (PM with aerodynamic diameter < 10 μm) effects on mortality and county-specific nickel or vanadium PM2.5 average concentrations using 1987-2000 effect estimates. We explored whether such modification is sensitive to outliers. METHODS: We estimated long-term average county-level nickel and vanadium PM2.5 concentrations for 2000-2005 for 72 U.S. counties representing 69 communities. We fitted Bayesian hierarchical regression models to investigate whether county-specific short-term effects of PM10 on mortality are modified by long-term county-specific nickel or vanadium PM2.5 concentrations. We conducted sensitivity analyses by excluding individual communities and considering log-transformed data. RESULTS: Our results were consistent with those of Lippmann et al. However, we found that when counties included in the NMMAPS New York community were excluded from the sensitivity analysis, the evidence of effect modification of nickel or vanadium on the short-term effects of PM10 mortality was much weaker and no longer statistically significant. CONCLUSIONS: Our analysis does not contradict the hypothesis that nickel or vanadium may increase the risk of PM to human health, but it highlights the sensitivity of findings to particularly influential observations. [ABSTRACT FROM AUTHOR]