Air pollution from farms leads to 17,900 US deaths per year, study finds Published May 10 Dust drifts over a cornfield in Alden, Iowa, on Aug. 28, 2017. Corn dominates the landscape and is primarily used for producing ethanol and feeding hogs. Iowa is the leading U.S. producer of corn and pork. (Bonnie Jo Mount / Washington Post) Share on Facebook Print article The smell of hog feces was overwhelming, Elsie Herring said. The breezes that wafted from the hog farm next to her mother’s Duplin County, N.C., home carried hazardous gases: methane, ammonia, hydrogen sulfide. “The odor is so offensive that we start gagging, we start coughing,” she told a congressional committee in November 2019. Herring said she and other residents developed headaches, breathing problems and heart conditions from the fumes.