Exposure to climate change-related extreme events in the first year of life and occurrence of infant wheezing

Introduction: Climate change increases the intensity and frequency of extreme events, which will most impact younger generations. Within the NINFEA birth cohort, we investigated the relationship between exposure to such events during the first year of life and infant respiratory health. Methods: The NINFEA cohort study recruited pregnant women across 11 years in Italy, allowing for climatic variability exploitation by birth place and time. We combined geocoded addresses with climate data, to derive children's cumulative exposure to the following extreme events during their first year: (i) heatwaves (i.e. 3 + consecutive days, with maximum temperature > 35 °C); (ii) days with wildfire PM2.5 >15 μg/m3 and (iii) daily precipitation > 100 mm; (iv) months with exceptional drought. Logistic regression models estimated the relationship between each exposure and wheezing at 6–18 months, adjusting for individual and contextual factors. Results: Wheezing prevalence in the cohort was 17.6%. The exposure to each additional heatwave in the first year of life increased wheezing risk by 16%, with an odds ratio (OR) of 1.16 and a 95% Confidence Interval (CI) of 1.00;1.35. The OR for each month of extreme drought exposure was 1.10, 95%CI 0.95; 1.26. Results for wildfire PM2.5 were unclear with wider confidence intervals (OR for each high exposure day:1.36, 95% CI 0.85; 2.16). Wheezing was not associated with extreme precipitation. Conclusions: Exposure to multiple extreme events, especially heatwaves, in the first year of life is associated with later infant respiratory health suggesting the need to implement climate change mitigation policies to protect long-term health.