Background-Large-scale animal feeding operations compromise regional air quality in the rural United States through emission of pollutants such as ammonia gas. Exposure to airborne pollution from animal feeding operations may cause pediatric asthma exacerbations in surrounding communities. Objectives-To describe spatial and temporal patterns in ambient ammonia concentrations in an agricultural region, and to investigate associations between short-term fluctuations in ammonia and subsequent changes in respiratory health in children with asthma. Methods-For 13 months in the Yakima Valley of Washington State, 14 monitors sampled ammonia in outdoor air for 24-hour periods every 6 days. School-age children with asthma (n=51) were followed for two health outcomes: biweekly reports of asthma symptoms and quick relief medication usage, and daily measurements of forced expiratory volume in one second (FEV1). We assessed associations between each outcome and ammonia using generalized estimating equations.

Background Large-scale animal feeding operations compromise regional air quality in the rural United States through emission of pollutants such as ammonia gas. Exposure to airborne pollution from animal feeding operations may cause pediatric asthma exacerbations in surrounding communities. Objectives To describe spatial and temporal patterns in ambient ammonia concentrations in an agricultural region, and to investigate associations between short-term fluctuations in ammonia and subsequent changes in respiratory health in children with asthma. Methods For 13 months in the Yakima Valley of Washington State, 14 monitors sampled ammonia in outdoor air for 24-hour periods every 6 days. School-age children with asthma (n=51) were followed for two health outcomes: biweekly reports of asthma symptoms and quick relief medication usage, and daily measurements of forced expiratory volume in one second (FEV1). We assessed associations between each outcome and ammonia using generalized estimating equations. Results 24-hour ammonia concentrations varied from 0.2 to 238.1 μg/m3 during the study period and displayed a strong correlation with proximity to animal feeding operations. FEV1% was 3.8% lower (95% CI: 0.2, 7.3) per interquartile increase in one-day lagged ammonia concentration and 3.0% lower (95% CI: 0.5, 5.8) for two-day lagged concentration. We observed no associations between self-reported asthma symptoms or medication usage and estimated ammonia exposure. Conclusions Ammonia concentrations were elevated in this community and strongly predicted by proximity to animal feeding operations. Ammonia's association with acute lung function decrements in children with asthma in the surrounding community may be causal or, alternatively, ammonia may be a marker for other pollutants from animal feeding operations associated with respiratory effects.