Early-Life air pollution and asthma risk in minority children the GALA II and SAGE II studies

Rationale: Air pollution is a known asthma trigger and has been associatedwith short-termasthmasymptoms,airway inflammation,decreased lung function, and reduced response to asthma rescuemedications. Objectives: To assess a causal relationship between air pollution and childhood asthma using data that address temporality by estimating air pollution exposures before the development of asthma and to establish the generalizability of the association by studying diverse racial/ethnic populations in different geographic regions. Methods: This study included Latino (n = 3,343) and African American (n=977) participants with and without asthma from five urban regions in the mainland United States and Puerto Rico. Residential history and data from local ambient airmonitoring stationswere used to estimate average annual exposure to five air pollutants: ozone, nitrogen dioxide (NO2), sulfur dioxide, particulatematter not greater than 10 mm in diameter, and particulatematter not greater than 2.5 mmindiameter. Within each region, we performed logistic regression to determine the relationship between early-life exposure to air pollutants and subsequent asthmadiagnosis.Arandom-effectsmodelwasusedtocombinetheregionspecific effects and generate summary odds ratios for each pollutant. Measurements and Main Results: After adjustment for confounders, a 5-ppb increase in average NO2 during the first year of life was associatedwith anodds ratio of 1.17 for physician-diagnosedasthma (95% confidence interval, 1.04-1.31). Conclusions: Early-life NO2 exposure is associated with childhood asthma in Latinos and African Americans. These results add to a growing body of evidence that traffic-related pollutants may be causally related to childhood asthma.