Temporal Variation of Association between Particulate Matters and Daily Deaths in Seoul, Korea

Abstract

Background: Although the mean concentration of ambient particulate matters (PM) and fine particulate matters (FPM) decreased, there is a possibility that the effects of PM and FPM on human health may increase over years. Previous studies suggested that the impact of increasing temperature on mortality and morbidity has also reduced because of physical and behavioral adaptation. Objectives: The purposes of this study are to estimate the association of PM and daily deaths, and to examine the existence of temporal variation in these associations. Methods: We used the daily counts of non-accidental deaths, cardiovascular deaths, respiratory deaths, air pollution and meteorological data in Seoul, Korea from 1998 to 2012. Generalized Additive Model (GAM) was used to estimate the PM effects on daily deaths and to examine the temporal variation of these association. Temperature, humidity, long-term time trend, and day of week were controlled in both analyses. Results: Total mortality in Korea had decreased, but the daily death counts had increased in 1998-2012. Mean daily concentrations of PM and FPM decreased steadily in the study period. With an increase of 10 ?/? in PM and FPM, the RR of daily non-accidental death counts increased by 0.30% [0.29-0.31] and 0.63% [0.61-0.66], respectively. The impacts of elevated concentrations of PM on total deaths and cardiovascular deaths declined, but increasing trends were shown during recent years. For respiratory deaths, the RRs increased steadily over 15 years in both all age group and old age group (65 and more). These variations may be due to the change in the composition of PM or the change in the ratio of FPM to PM. Conclusion: In this study, we found evidence that there are temporal variations in the association between PM and daily deaths. Our results should be considered in studies on environmental burden of disease or impact assessment of air pollution.