Study objectives: To examine whether or not the presence of mist or fog affects respiratory conditions in asthmatic children.
Design: A retrospective study. PREPARATION AND METHODS: There were 754 visits by children with asthma to the emergency room at night (between 18:00 p.m. and 9:00 a.m.) during a two-year period. Meteorological data were checked at a local fire station and regional meteorological observatory. We evaluated the relation between meteorological data and the number of emergency room visits of asthmatic children.
Results: The mean number of asthmatic children who visited the emergency room was higher on misty or foggy nights than on clear nights (1.2 +/- 1.2 people/night vs. 0.8 +/- 0.9 people/night, p<0.0001). Mist and fog had an increased odds ratio (OR) of emergency room visits of asthmatic children (1.74, p<0.001). In addition, increased OR was found for high atmospheric temperature (4.39, p<0.0001). Multivariate analysis showed mist and fog (p<0.0001), average atmospheric temperature (p<0.0001), and day-to-day change of temperature (p<0.05) were related to the number of asthmatic children (n=731, r=0.428, p<0.0001).
Conclusions: Our results suggest that the presence of mist and fog causes the exacerbation of asthma in children. It is not clear which is related to the high frequency of emergency room visits of asthmatic children, airborne water droplets or the meteorological condition that causes mist or fog, but the prophylaxis for exacerbation may decrease the frequency of emergency room visits.