Effects of policy-driven hypothetical air pollutant interventions on childhood asthma incidence in southern California

Significance Asthma is one of the leading chronic diseases among children, and there is increasing evidence that air pollution plays a role in the development of this disease. We found that had NO 2 or PM 2.5 concentration in 9 southern Californian communities been lower than observed in the 1990s and early 2000s, there would have been a corresponding reduction in childhood asthma incidence, with larger effect estimates for NO 2 . Our findings may have implications for air quality regulations, as all communities examined in this study had ambient concentrations well below the current US Environmental Protection Agency annual standard of 53 ppb for NO 2 .