Associations between hourly PM2.5 chemical constituents and emergency department visits for cardiovascular and respiratory disease

Abstract

Introduction : Several epidemiological studies have investigated fine particulate matter (≤ 2.5 μm in aerodynamic diameter, PM2.5) has a risk for adverse effects on human health. Previous studies have focused on the risk associated with the total mass of particles, without considering the chemical constituents of them. In this study, the hourly differences between PM2.5 chemical constituents and emergency visits for cardiovascular disease and respiratory disease were estimated using time-stratified case-crossover design. Methods: The study periods were from January 1 to December 31, 2013 in Seoul, Korea. Hourly health outcome data on emergency department visits for cardiovascular disease and respiratory disease were provided by National Emergency Department Information System (NEDIS). Emergency department visits data were classified according to the discharge diagnosis for cardiovascular disease and respiratory disease (ICD-10, cardiovascular, I00-I99 and respiratory, J00-J99). Hourly data for PM2.5 mass and chemical constituents were measured by real-time monitoring at one sampling site located at Bulgwang-dong, Seoul (37.36° N, 126.56° E). In this study, PM2.5 mass and only 13 chemical constituents (OC, EC, Cl-, Mg2+, Na+, NH4+, NO3-, SO42-, Ca, Fe, K, Pb, and Zn), were selected after QA/QC procedure. The meteorological data such as hourly mean temperature (℃), relative humidity (%), and air pressure (hPa) were adjusted as confounding variable. Time-stratified case-crossover analysis and conditional logistic regression analysis were used to estimate the adverse health effects of fine air particles and to estimate and adjusted odds ratio (ORs) and 95% confidence intervals (CIs), respectively. The short-term effects were estimated using moving averages in six periods (1-6(h), 7-12(h), 13-18(h), 19-24(h), 25-48(h), 49-72(h)) and adjustments of this association by age (≥ 65 years) and season. Results and Discussion : The strongest adverse effects for cardiovascular disease exacerbations were associated with PM2.5 mass, OC, EC, Cl-, Ca, Fe and Zn after 19-24h lag period and NH4+, NO3-, and SO42- after 25-48h lag period were estimated. The strongest adverse effects for respiratory disease exacerbations were associted with NO3-, K and Pb after short lag periods (0-6h and 7-12h) and PM2.5, OC, EC, Cl-, NH4+, SO42-, Ca, Fe, and Zn after longer lag periods (19-24h and 25-48h). For those older than ≥ 65 years, the strongest adverse effects for cardiovascular disease exacerbations were shown with PM2.5 mass, OC, EC, Cl-, Ca, Fe, and Zn after 19-24h lag period and NO3- after 25-48 h lag period and respiratory disease exacerbations of OC, EC, Fe and Zn after 19-24h lag period were observed. Especially, among PM2.5 chemical constituents, EC showed the strongest association with cardiovascular disease and respiratory disease exacerbations. For all of seasons, significant positive associations for PM2.5 mass and chemical constituents excluding Mg2+ were observed for cardiovascular and respiratory disease. Conclusion : This study found major differences of associations between PM2.5 constituents and emergency visits for cardiovascular and respiratory disease in Seoul. This study will provide robust evidences for the health impacts of PM2.5 chemical constituents.