Methods: We used daily hospital admissions for respiratory diseases in Busan from hospital records using the International Classication of Diseases (ICD-10) for the period 2007-2010. The respiratory allergic diseases used in our study are allergic rhinitis (J30) and asthma (J45-46). Age was categorized as group I (0-15), group II (16-64) and group III (≥ 65 yr). Hourly particulate matter < 10µm (PM10) levels and particulate matter < 2.5µm (PM2.5) levels were obtained from 19 monitoring stations in Busan, and collected by and made available from the Korean Ministry of Environment. The meteorological observation data in Busan provided by the Korean Meteorological Administration included temperature and relative humidity.
Results: The mean value of hospital admission for allergy rhinitis and asthma was 4.4±6.1 people and 3.3±3.3 people respectively. A daily-average value of PM10 and PM2.5 concentrations level was 49.6±20.5 µg/m3 and 24.2±10.9 µg/m3 respectively. The mean temperature was 15.1±7.9°C, relative humidity was 62.0±18.0%. Admission for allergic rhinitis was associated with increasing temperature anomaly (P=0.003) and decreasing relative humidity (P<0.001). When the relative humidity was constant, the increase in PM10 levels was significantly associated with higher admission for allergic rhinitis. In asthma, hospitalization was correlated with decreasing relative humidity (P<0.001) and increasing PM10 (P=0.008). Even after considering relative humidity, higher PM10 levels still were associated with higher hospitalization rate. In subgroup analysis according to age, admission rate in group I and group III was more strongly affected by PM10 levels than group II (IRR 7.4 and 6.4, respectively). Furthermore, it showed the association between higher PM2.5 levels and admission for asthma, regardless of the effect of PM10levels.
Conclusions: Particulate matter levels and meteorological factors have an effect on hospitalization for allergic rhinitis or asthma. After adjusting meteorological factors, PM10 or PM2.5 levels increase significantly admission rate for respiratory allergic diseases.