Identifying Critical Windows and Joint Effects of Prenatal Air Pollution and Temperature Exposure and Lung Function in Schoolchildren: Findings From a Prospective Birth Cohort Study

Background: Air pollution and extreme temperature exposure during pregnancy is associated with lung function in schoolchildren. Research Question: What are the critical time windows during pregnancy when exposure to air pollution (fine particulate matter [PM_2.5] and nitrogen dioxide [NO₂]) and temperature affects lung function in schoolchildren, and do these exposures interact? Study Design and Methods: Within the Programming Research in Obesity, Growth, Environment, and Social Stressors study, daily residential levels of pollutant/temperature exposures during pregnancy were generated from satellite-based models. Lung function was evaluated at ages 8 to 14 years and was modeled as z scores adjusted for age, height, and sex. We used distributed lag nonlinear models to evaluate overall and sex-specific associations of exposures with lung function outcomes. Interactive effects were evaluated through the relative excess risk due to interaction and the attributable proportion. Results: A total of 429 mother-child dyads were included. Prenatal higher PM_2.5 exposure was associated with reduced lung function parameters, including FEV₁ z score (weeks 1-21, cumulative change: –0.23 [95% CI, –0.39 to –0.07]), FVC z score (weeks 13-19, cumulative change: –0.04 [95% CI, –0.08 to –0.00]), forced expiratory flow at 25% to 75% of vital capacity (FEF_25–75%) z score (weeks 1-20, cumulative change: –0.20 [95% CI, –0.36 to –0.04]), and FEV₁/FVC ratio (weeks 6-16, cumulative change: –0.57 [95% CI, –0.11 to –0.04]). Similarly, increased NO₂ exposure was associated with reduced FEV₁ z score (weeks 1-16, cumulative change: –0.16 [95% CI, –0.31 to –0.02]), FEF_25–75% z score (weeks 13-16, –0.02 [95% CI, –0.04 to –0.00]), and FEV₁/FVC ratio (weeks 6-15, –0.48 [95% CI, –0.96 to –0.01]). In contrast, both warmer (weeks 1-8) and colder temperatures (weeks 9-18) showed positive associations with FVC z score. Stronger associations were found in female participants. No interactive effects of air pollution and temperature were found. Interpretation: Our findings emphasize detrimental effects of early-life air pollution exposure on long-term respiratory health and suggest potential sex-specific vulnerabilities, informing targeted interventions to protect child health.