A Holstein cow stands on top of a pile of manure. Manure gives off ammonia which causes particulate air pollution. (Damian Dovarganes / The Associated Press)
A Holstein cow stands on top of a pile of manure. Manure gives off ammonia which causes particulate air pollution. (Damian Dovarganes / The Associated Press)
A Holstein cow stands on top of a pile of manure. Manure gives off ammonia which causes particulate air pollution. (Damian Dovarganes / The Associated Press)