Effects of diurnal temperature changes on asthmatic children: An ecological study

Background and purpose: The prevalence of childhood asthma increased in Taiwan despite of air pollution control. This ecological study evaluates the effect of diurnal temperature changes on exacerbation of asthma and its possible mechanisms. Methods: Data on both climate factors and air pollutants were obtained from the governamental agencies. Of the 365 days in the study period, the case group is defined as the days with admissions for asthma and the other days are classified as the control group. The days with admissions is defined as the days when patients under 18 years of age were admitted to hospitals with the chief problem of asthma. 7,623 patients with asthma (age ≤ 18) were assessed and the characteristics between these two groups were compared, including diurnal temperature changes. Multiple linear regressions were used to assess the effects of both temperature changes and air pollutants. Results: The effects of diurnal temperature changes were relatively consistent in a given geographic area in a specific season. In winter, there were positive associations in regions southern to the Tropic of Cancer and negative associations in northern regions. In other seasons, there were positive associations in plain regions near the sea and negative associations in mountainous regions away from the sea. Conclusions: Diurnal changes of temperature themselves may affect symptoms of childhood asthma in different ways, and the effects vary across different geographic areas and seasons. The varied effects may cause exacerbation of symptoms in children through the mechanism of physical accommodation.