Hydrogen sulfide concentrations at three middle schools near industrial livestock facilities.

Safe school environments are essential for healthy development, yet some schools are near large-scale livestock facilities that emit air pollution. Hydrogen sulfide (H2S) from decomposing manure is an indicator of livestock-related air pollution. We measured outdoor concentrations of H2S at three public middle schools near livestock facilities in North Carolina. We used circular graphs to relate H2S detection and wind direction to geospatial distributions of nearby livestock barns. We also used logistic and linear regression to model H2S in relation to upwind, distance-weighted livestock barn area. Circular graphs suggested an association between upwind livestock barns and H2S detection. The log-odds of H2S detection per 1000 m2 increased with upwind weighted swine barn area (School A: β-coefficient (β)=0.43, SE=0.06; School B: β=0.64, SE=0.24) and upwind weighted poultry barn area (School A: β=0.05, SE=0.01), with stronger associations during periods of atmospheric stability than atmospheric instability (School A stable: β=0.69, SE=0.11; School A unstable: β=0.32, SE=0.09). H2S concentration also increased linearly with upwind swine barn area, with greater increases during stable atmospheric conditions (stable: β=0.16 parts per billion (p.p.b.), SE=0.01; unstable: β=0.05 p.p.b., SE=0.01). Off-site migration of pollutants from industrial livestock operations can decrease air quality at nearby schools.