Air Pollution and Hospital Admissions for Ischemic Heart Diseases among Individuals 64+ Years of Age Residing in Seoul, Korea

Abstract

There is increased evidence that air pollution may be associated with cardiovascular disease. The authors' prior investigations on the association between air pollution exposure and stroke mortality led to the current study, which was conducted to assess the effects of ambient air pollution on ischemic cardiovascular diseases among the elderly population (i.e., males and females 64+ yr of age) in Seoul, Korea. The authors estimated the relative risks of hospitalization associated with an interquartile range (IQR) increase in pollution concentrations; a generalized additive Poisson model was used to conduct a time-series analysis of the counts. The concentrations of ambient air pollutants were lower than the current recommendations for air quality in Korea. The estimated relative risks of hospitalization associated with an IQR were 1.05 (95% confidence interval [CI] = 1.01, 1.10) for particulate matter less than or equal to 10 microm in diameter (PM10) (IQR = 40.4 microg/m3); 1.10 (95% CI = 1.05, 1.15) for ozone (IQR = 21.7 ppb); 1.08 (95% CI = 1.03, 1.14) for nitrogen dioxide (IQR = 14.6 ppb); 1.07 (95% CI = 1.01, 1.13) for carbon monoxide (IQR = 1.0 ppm); and 0.95 (95% CI = 0.90, 1.01) for sulfur dioxide (IQR = 4.4 ppb). The authors observed that sulfur dioxide was a significant risk factor for ischemic heart disease-related hospital admissions during the summer months (i.e., June, July, and August) (relative risk = 1.32; 95% CI = 1.08, 1.62). Hospital admissions for ischemic heart diseases were associated significantly with daily variations in levels of ambient air pollutants. These findings may provide new insights into the possible pathologic mechanisms involving air pollutants, and they support the hypothesis that the elderly appear to be at particular risk from the effects of air pollution, at pollutant levels lower than the standards commonly adopted by many countries.