Estimation of the Effect of Hypothetical Air Pollution Scenarios on Lung Function in the Southern California Children's Health Study: An Application of G-Computation

Background: We have shown improved lung function with decreasing pollutant levels across several cohorts from the Southern Californian Children’s Health Study (CHS). In this study, we estimate the benefits of air pollution reduction on lung function growth under several hypothetical scenarios by implementing g-computation, a method based in the counterfactual framework.Methods: Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were assessed repeatedly among 2120 adolescents across 3 CHS cohorts spanning nearly 2 decades. Averages of regional nitrogen dioxide (NO2) and particulate matter ≤2.5 µm (PM2.5) were taken from 1994-1998, 1997-2001, and 2007-2011, which correspond to lung growth from 11 to 15 years of age in these cohorts. Mixed-effects linear regression models, incorporating regional pollutants and key covariates, were used to model growth trajectory for each lung function measure from age 11 to 15. Compared to lung function growth based on observed data, we e...