Short-term effects of air pollution on hospital admissions in Korea

BACKGROUND:: Numerous studies have identified short-term effects of air pollution on morbidity in North America and Europe. The effects of air pollution may differ by region of the world. Evidence on air pollution and morbidity in Asia is limited. METHODS:: We investigated associations between ambient air pollution and hospital admissions in eight Korean cities for 2003-2008. We applied a two-stage Bayesian hierarchical model to estimate city-specific effects and the overall effects across the cities. We considered lagged effects of pollutants by cause (allergic disease, asthma, selected respiratory disease, and cardiovascular disease), sex, and age (0-14, 15-64, 65-74, and ≥75 years). RESULTS:: We found evidence of associations between hospital admissions and short-term exposure to air pollution. An interquartile range (IQR) increase in PM₁₀ (30.7μg/m³) was associated with an overall increase of 2.2% (95% posterior interval = 0.5%-3.9%), 2.8% (1.3%-4.4%), 1.7% (0.9%-2.6%), and 0.7% (0.0%-1.4%) in allergic, asthma, selected respiratory, and cardiovascular admissions, respectively. For NO₂ (IQR 12.2 ppb), the corresponding figures were 2.3% (0.6%-4.0%), 2.2% (0.3%-4.1%), 2.2% (0.6%-3.7%), and 2.2% (1.1%-3.4%). For O₃, we found positive associations for all the studied diagnoses except cardiovascular disease. SO₂ was associated with hospital admissions for selected respiratory or cardiovascular causes, whereas O₃ was negatively associated with cardiovascular admissions. We found suggestive evidence for stronger associations in younger and older age groups. Associations were similar for men and women. CONCLUSIONS:: Ambient air pollution was associated with increased risk of hospital admissions in Korea. Results suggest increased susceptibility among the young or the elderly for pollution effects on specific diseases.