The Impact of Extreme Heat Waves and Air Pollution on the Prognosis of Chronic Airway Diseases

Climate change has led to a global increase in temperatures, and according to NASA, 2024 was the hottest year on record since 1850. Extreme heatwaves (EHW) represent one of the most significant manifestations of this crisis. While the adverse effects of air pollution on chronic respiratory diseases are well documented, the impact of extreme heatwaves on asthma and chronic obstructive pulmonary disease (COPD) has received less attention. This study was designed to prospectively evaluate the effects of extreme heatwaves and air pollution on patients with asthma and COPD. The study was conducted in Mersin, Türkiye, between February and December 2024. Individuals with physician-diagnosed asthma or COPD who attended the outpatient clinic were enrolled. Baseline assessments were performed on days with normal seasonal weather. Lung function was measured using spirometry, and airway inflammation was assessed using fractional exhaled nitric oxide (FeNO). Symptom control and quality of life were measured using validated questionnaires: the Asthma Control Test (ACT) and Asthma Quality of Life Questionnaire (AQLQ) for patients with asthma, and the Modified Medical Research Council (mMRC) scale and COPD Assessment Test (CAT) for patients with COPD. Meteorological variables, including temperature, humidity, and wind, as well as daily air pollution levels, were obtained from official sources. On documented extreme heatwave days, participants were recalled for follow-up visits. At these visits, spirometry, FeNO, and questionnaire assessments were repeated. Information regarding exacerbation episodes requiring systemic corticosteroid use or hospitalization during the study period was also collected. The study was designed to compare patient-level outcomes between normal weather days and extreme heatwave days. The overall objective was to investigate how environmental stressors such as heat and air pollution influence disease control, quality of life, symptoms, lung function, and airway inflammation in patients with asthma and COPD.