Associations Between Fine Particulate Matter Components and Daily Mortality in Nagoya, Japan.

Kayo Ueda,Makiko Yamagami,Fumikazu Ikemori,Kunihiro Hisatsune,Hiroshi Nitta

doi:10.2188/jea.je20150039

Abstract

BackgroundSeasonal variation and regional heterogeneity have been observed in the estimated effect of fine particulate matter (PM2.5) mass on mortality. Differences in the chemical compositions of PM2.5 may cause this variation. We investigated the association of the daily concentration of PM2.5 components with mortality in Nagoya, Japan.MethodsWe combined daily mortality counts for all residents aged 65 years and older with concentration data for PM2.5 mass and components in Nagoya from April 2003 to December 2007. A time-stratified case-crossover design was used to examine the association of daily mortality with PM2.5 mass and each component (chloride, nitrate, sulfate, sodium, potassium, calcium, magnesium, ammonium, elemental carbon [EC], and organic carbon [OC]).ResultsWe found a stronger association between mortality and PM2.5 mass in transitional seasons. In analysis for each PM2.5 component, sulfate, nitrate, chloride, ammonium, potassium, EC, and OC were significantly associated with mortality in a single-pollutant model. In a multi-pollutant model, an interquartile range increase in the concentration of sulfate was marginally associated with an increase in all-cause mortality of 2.1% (95% confidence interval, −0.1 to 4.4).ConclusionsThese findings suggest that some specific PM components have a more hazardous effect than others and contribute to seasonal variation in the health effects of PM2.5.

Highlights

Epidemiological studies have shown an association between mortality and short-term exposure to particulate matter (PM)
While cardiovascular mortality was significantly associated with chloride, elemental carbon (EC), and organic carbon (OC) at lag 0, respiratory mortality was significantly associated with sulfate at lag 0, nitrate at lag 2, ammonium at lag 0 and lag 2, and potassium at lag 0
Season-stratified analysis showed a stronger association of PM2.5 mass with all-cause mortality in transitional seasons than in summer and winter

Summary

Introduction

Epidemiological studies have shown an association between mortality and short-term exposure to particulate matter (PM). PM is a complex mixture of particles with various sizes and chemical compositions, and there is interest in whether this variation is responsible for differences in target health outcomes and effect size estimates. Several multi-city studies have suggested regional heterogeneity in the estimated effect of PM on mortality[3,4,5] and hospitalization.[6,7] Seasonal variation has been found to affect estimates of PM effects.[6,8] These regional and seasonal variations are partly explained by community characteristics, such as air-conditioning prevalence,[8] population density,[9] proportion of elderly residents,[10] and effect modification by ambient temperature.[11] Seasonal and regional variations in the chemical composition of ambient particles have been suggested to contribute to heterogeneity in PM health effects. Seasonal variation and regional heterogeneity have been observed in the estimated effect of fine particulate matter (PM2.5) mass on mortality. Conclusions: These findings suggest that some specific PM components have a more hazardous effect than others and contribute to seasonal variation in the health effects of PM2.5

Methods

Results

Conclusion