Assessing the meteorological triggers of childhood asthma: A season-stratified time-series analysis

Abstract

Background: Although there has been increasing interest in identifying the adverse effects of outdoor environmental factors on asthma exacerbations (AE), few studies have examined the season-stratified effects of outdoor meteorological factors on childhood AE, especially in developing countries. Objective: We explored the effects of meteorological factors on childhood AE and the modification effects by season in Shanghai, China. Methods: We used a Poisson generalized linear regression model combined with a distributed lag nonlinear model to examine the lagged and nonlinear effects of meteorological factors on childhood AE in Shanghai from 2008 to 2017. We also performed a season-stratified analysis to determine the modification effects of meteorological conditions by season on AE after adjustment for a range of potential confounders.Results: There were 23,103 emergency department visits (EDVs) for childhood AE, including 15,466 boys and 7,637 girls. Both non-optimal temperatures and relative humidity (RH) were significantly associated with daily EDVs for childhood AE (e.g., cumulative relative risk (CRRlag0-28) for the 95th percentile of temperature: 2.196, 95% CI: 1.128, 4.286; CRRlag0-28 for the 5th percentile of RH: 3.217, 95% CI: 1.734, 6.365). In the cold season, lower temperatures were related to elevated CRR for childhood AE, while in the warm season, higher temperatures were associated with increased CRR for childhood AE. Lower levels of RH elevated the risk of childhood AE in both cold and warm seasons.Conclusion: Non-optimal temperatures and relative humidity were major triggers of emergency department visits for childhood AE. However, the effects of meteorological conditions on childhood AE varied by season. It is essential to develop season-specific, tailored strategies to prevent and control childhood AE.