Associations between ambient fine and coarse particles and mortality in major cities of Korea

Abstract

Introduction While many epidemiological studies have examined the health effects of different size of ambient particulate matter (PM), findings have been mixed. PM is a heterogeneous mixture of particles, and its chemical components differ by size with more combustion related materials in fine mode and more crustal materials in coarse mode. This study estimates risk of mortality associated with PM2.5 (less than 2.5 ㎛ in aerodynamic diameter) and PM2.5-10 (less than 10 ㎛ and greater than 2.5 ㎛ in aerodynamic diameter) exposure. Methods Long-term measurements of PM2.5 and PM2.5-10 were compared with all-cause, cardiovascular, and respiratory mortality observed from January 2006 through December 2012 in three large cities (i.e. Seoul, Incheon, and Busan), Korea. A time-series analysis with a Generalized Additive Model (Quasi-Poisson distribution) was used to evaluate associations of PM2.5 and PM2.5 with mortality. Results A 10 μg/m3 increase in PM2.5 (lag01) was associated with an increase of 1.18% (95% CI: 0.64, 1.72), 0.34% (95% CI: 0.03, 0.64), and 0.43% (90% CI: 0.02, 0.95) in all-cause mortality in Busan, Seoul, and Incheon, respectively, during the study period. 0.52% (95% CI: 0.09, 0.96) and 2.25% (95% CI: 0.38, 4.15) increases in respiratory mortality were associated with a 10 μg/m3 increase in PM2.5 (lag01) in Seoul and Busan, respectively. Overall, associations were stronger in Busan than other cities, and among those ≥ 65 than < 65 years of age. Associations with PM2.5-10 were positive but smaller than PM2.5 in magnitude. Conclusions Statistically significant associations between ambient PM2.5 and PM2.5-10 and mortality were observed in this study. Exposure to fine particles, which mostly originate from combustion and mobile emissions, shows stronger effects on human health than coarse particles, which mostly originate from natural sources such as soil and mechanical processes.