Abstract Introduction Exposure to extreme ambient temperatures has been associated with impaired lung function in children with asthma. However, the impact of temperature variability on bronchodilator response remains unclear. This study evaluated the association of daily temperature variability and bronchodilator response among children with persistent asthma in two peri-urban communities in Lima, Peru. Materials and Methods In this cross-sectional study, children aged 9 – 17 years living in Pampas de San Juan and Sector-I of Villa El Salvador (southern Lima) were screened between July 2024 and January 2025. Screening included an asthma symptoms questionnaire and pre- and post-bronchodilator (400 µg salbutamol) spirometry following ATS/ERS guidelines. Children who were identified as having persistent asthma according to the National Asthma Education and Prevention Program (NAEPP) criteria were enrolled for longitudinal follow-up. Lung function indices considered were bronchodilator responsiveness (difference between post and pre-bronchodilator values) in FEV1, FVC, and FEV1/FVC z-scores, calculated using the GLI-2012 mixed-ethnicity population equations. Hourly temperature data were obtained from a government-run environmental monitor located 5 km away from the study site. Fine particulate matter (PM2.5) and relative humidity (RH) levels were obtained from a low-cost environmental monitor located outside the study site office (S12°11’0.193”, O76°57’38.376”). Daily temperature variability (ΔT°) was defined as the absolute difference between the lowest and highest ambient temperatures in the 24-hour window prior to the spirometry test. We used distributed lag non-linear models with up to seven lags to evaluate the association between bronchodilator changes in lung function and ΔT° (β-coefficient) adjusted for PM2.5lag0-7, RHlag0-7, age, sex, and body mass index. Results Among 144 children with persistent asthma identified during screening, 41 were severe, 35 moderate, and 68 mild. Pre-bronchodilator FEV1, FVC and FEV1/FVC z-scores were 0.84±1.39, 1.64±1.31, and -1.11±1.12, respectively, while post-bronchodilator values were 1.58±1.32, 1.72±1.26 and -0.20±0.97, respectively. Mean ΔT° at lag0 was 4.26±1.79oC (range 0.7 °C and 9.6 °C). A non-significant increasing cumulative effect of ΔT° across lags 0-7 was observed for bronchodilator change in FEV1/FVC, with lag0-7 effects of 0.30 (95%CI -0.06;0.65), 0.12 (-0.10;0.33), -0.03 (-0.20;0.14), -0.11 (-0.31;0.08), -0.10 (-0.29;0.09), 0.01 (-0.17;0.18), 0.18 (-0.07;0.42), and 0.38 (-0.02;0.78), respectively, for a ΔT° of 1 °C. Conclusions Daily temperature variability was not associated with bronchodilator response in children with persistent asthma. This abstract is funded by: NIH
Fano-Sizgorich et al. (Fri,) studied this question.