Ambient Ammonia Exposures in an Agricultural Community and Pediatric Asthma Morbidity

Abstract

Ambient Ammonia Exposures in an Agricultural Community and Pediatric Asthma MorbidityAbstract Number:2786 Christine Loftus*, Michael Yost, Griselda Arias, Elizabeth Torres, Maria Tchong, Jenna Armstrong, Kris Hartin, and Catherine Karr Christine Loftus* University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Michael Yost University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Griselda Arias Yakima Valley Farm Workers Clinic, United States, E-mail Address: [email protected] Search for more papers by this author , Elizabeth Torres Radio KDNA, United States, E-mail Address: [email protected] Search for more papers by this author , Maria Tchong University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , Jenna Armstrong National Institute for Occupational Safety and Health, United States, E-mail Address: [email protected] Search for more papers by this author , Kris Hartin University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author , and Catherine Karr University of Washington, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Large scale animal feeding operations (AFOs) compromise regional air quality in the rural United States, including by emission of ammonia gas. Exposure to airborne AFO pollution is suspected of causing pediatric asthma exacerbations in surrounding communities.Objectives: To describe spatial and temporal patterns in ambient ammonia concentrations in an agricultural region of Washington State, and to explore associations between short-term fluctuations in ammonia and subsequent changes in respiratory health for children with asthma.Methods: For 13 months in the Yakima Valley, 14 air monitors sampled outdoor air in 24- hour periods at six day intervals, and ambient ammonia concentrations were calculated. 51 school-aged children with asthma were followed over the same period for two health outcomes: biweekly reports of asthma severity using the Asthma Control Questionnaire (ACQ), and daily measurements of forced expiratory volume in one second (FEV1). Epidemiologic associations between each outcome and ammonia were assessed using generalized estimating equations.Results: 24-hour ammonia concentrations varied from 0.2 to 238.1 ug/m3 during the study period, and median concentrations by site displayed a strong correlation with AFO proximity. FEV1 as a percent of predicted values was 4.0% lower (96%CI: 0.7, 7.3) per interquartile increase in one-day lagged NH3 measurements and 3.3% lower (96%CI: 0.5, 6.3) for two-day lagged exposure assessment. No associations between results of the ACQ and estimated NH3 exposure were observed.Conclusions: Community-level ammonia concentrations were elevated in this region and strongly predicted by AFO proximity. Exposure to ammonia might cause lung function decrements in children with asthma in the surrounding community. Alternatively, ammonia may serve as a marker for other components of AFO emissions, and lung function decrements may be caused by exposure to overall AFO ‘plumes.’