Individual and neighborhood factors influencing pediatric asthma exacerbations during urban heatwaves

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Anthropogenic greenhouse gas emissions and urbanization have altered atmospheric conditions, increasing the frequency and intensity of extreme heat events. In response, Philadelphia issues a "Code-Red" heat health warning when temperatures exceed 95°F for three consecutive days. However, this threshold may be too high to protect vulnerable populations, including children with asthma. We conducted a case-crossover study to evaluate associations between heatwave intensity and duration and pediatric asthma exacerbations from March to August 2011-2016, in Philadelphia, PA. Exacerbations were identified using electronic health records from the Children's Hospital of Philadelphia. Conditional logistic regression models estimated associations, and we assessed effect modification by individual characteristics and neighborhood factors. Odds of asthma exacerbation were 15% higher following two consecutive days above the 95th percentile of daily maximum temperatures (93.5°F) compared to cooler days (OR: 1.15; 95% CI: 0.98-1.34). Estimates of associations were stronger among children aged 5-12 years (OR: 1.26; 95% CI: 0.97-1.63) and those living in racially and economically segregated neighborhoods (OR: 1.19; 95% CI: 1.00-1.42). These findings, though statistically insignificant, may suggest that local heat advisories could benefit from considering lower temperature thresholds and shorter duration criteria; however, additional studies are needed to further evaluate these associations.