We assessed the association of fluctuations in ambient temperature, air pollutants, and Asian dust (AD) events with the hospitalization of children for asthma in Fukuoka City.
Data on emergency hospitalizations of children under 12 years of age for asthma were collected at Fukuoka National Hospital. We obtained air pollution and meteorological data for Fukuoka from the National Institute for Environmental Studies. Using a time-stratified case-crossover design, we estimated odds ratios (ORs) of hospitalization corresponding to a unit change in weather variables and concentration of air pollutants. We also evaluated the effect of AD events on asthma hospitalization with data stratified by days with or without an AD event.
There were 3427 hospitalizations and 106 AD events from 2001 to 2007. We found that within-day temperature change rather than ambient temperature was associated with asthma exacerbation. In the multi-pollutant model, the ORs per 1°C within-day drop and rise during the period from the hospitalization day to 3 days previously (lag3) were 1.033 [95% confidence interval (CI) 1.005–1.063] and 1.027 (95% CI 0.995–1.060), rspectively. A 10 μg/m3 increase in suspended particulate matter (SPM) and nitrogen dioxide (NO2) at lag2–lag3 were significantly associated with an increase in asthma hospitalization with ORs of 1.041 (95% CI 1.013–1.070) and 1.112 (95% CI 1.022–1.209), respectively. We did not observe a significant association between asthma hospitalization and AD events.
This study showed that temperature fluctuation, SPM, and NO2 were associated with an increased risk of hospitalization of children for asthma.