Extreme weather and asthma: a systematic review and meta-analysis

Background: Climate change’s influence on extreme weather events poses a significant threat to the morbidity and mortality of asthma patients. The aim of this study was to examine associations between extreme weather events and asthma-related outcomes. Methods: A systematic literature search for relevant studies was performed using the PubMed, EMBASE, Web of Science and ProQuest databases. Fixed-effects and random-effects models were applied to estimate the effects of extreme weather events on asthma-related outcomes. Results: We observed that extreme weather events were associated with increasing risks of general asthma outcomes with relative risks of 1.18-fold for asthma events (95% CI 1.13–1.24), 1.10-fold for asthma symptoms (95% CI 1.03–1.18) and 1.09-fold for asthma diagnoses (95% CI 1.00–1.19). Extreme weather events were associated with increased risks of acute asthma exacerbation with risk ratios of asthma emergency department visits of 1.25-fold (95% CI 1.14–1.37), of asthma hospital admissions of 1.10-fold (95% CI 1.04–1.17), of asthma outpatient visits of 1.19-fold (95% CI 1.06–1.34) and of asthma mortality of 2.10-fold (95% CI 1.35–3.27). Additionally, an increase in extreme weather events increased risk ratios of asthma events by 1.19-fold in children and 1.29-fold in females (95% CI 1.08–1.32 and 95% CI 0.98–1.69, respectively). Thunderstorms increased the risk ratio of asthma events by 1.24-fold (95% CI 1.13–1.36). Conclusions: Our study showed that extreme weather events more prominently increased the risk of asthma morbidity and mortality in children and females. Climate change is a critical concern for asthma control.