J Prev Med Public Health.
2006 Jul;39(4):309-316.
Effects of Air Pollution on Asthma in Seoul: Comparisons across Subject Characteristic
- Affiliations
-
- 1Department of Epidemiology and Biostatistics, School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Korea. hokim@snu.ac.kr
- 2Environmental and Occupational Health Sciences, School of Public Health and Community Medicine, University of Washington, Seattle, USA.
- 3Primary Health Care Team, Research Department, Korea Health Insurance Review Agency, Seoul, Korea.
Abstract
- OBJECTIVES: Korean epidemiological studies have used reduced samples according to the subject's characteristics, such as the health services provided, the historical note with asthma, and age, to examine the acute effect of air pollution on asthma using the Korean National Health Insurance records. However, there have been few studies on whether the effects shown in these reduced samples are different from those of all samples. This study compared the effects of air pollution on asthma attacks in three reduced samples with those of entire samples. METHODS: The air pollution data for PM10, CO, SO2, NO2, and O3 and weather conditions including temperature, relative humidity, and air pressure in Seoul, 2002, were obtained from outdoor monitoring stations in Seoul. The emergency hospital visits with an asthma attack in Seoul, 2002 were extracted from the Korean National Health Insurance records. From these, the reduced samples were created by health service, historical notes with asthma, and age. A case-crossover design was adopted and the acute effects of air pollution on asthma were estimated after adjusting for weather, time trend, and seasonality. The model was applied to each reduced sample and the entire sample. RESULTS: With respect to the health service, the effects on outpatients were similar to those for the total sample but were different for inpatients. These similar effect sizes were also observed in the reduced samples according to the historical note with asthma and age. The relative risks of PM10, CO, SO2, NO2, and O3 among the reduced and entire samples were 1.03, 1.04-1.05, 1.02-1.03, 1.04-1.06, and 1.10-1.17, respectively. CONCLUSIONS: There was no clear evidence to show a difference between the reduced samples and the entire samples.
