CAFOs contribute to the reduction of ambient air quality. CAFOs release several types of gas emissions—ammonia, hydrogen sulfide, methane, and particulate matter—all of which bear varying human health risks. The amount of gas emissions depends largely on the size of the CAFO. The primary cause of gas emissions from CAFOs is the decomposition of animal manure being stored in large quantities. Additionally, CAFOs emit strains of antibiotic resistant bacteria into the surrounding air, particularly downwind from the facility. Levels of antibiotics measured downwind from swine CAFOs were three times higher than those measured upwind. While it is not widely known what is the source of these emissions, the animal feed is suspected.Globally, ruminant livestock are responsible for about 115 Tg/a of the 330 Tg/a (35%) of anthropogenic greenhouse gas emissions released per year."Trace Gases: Current Observations, Trends, and Budgets", Climate Change 2001, IPCC Third Assessment Report. IPCC/United Nations Environment Programme Livestock operations are responsible for about 18% of greenhouse gas emissions globally and over 7% of greenhouse gas emissions in the U.S.David N. Cassuto, The CAFO Hothouse: Climate Change, Industrial Agriculture and the Law Methane is the second most concentrated greenhouse gas contributing to global climate change,EPA (1999). "U.S. methane emissions 1990–2020: Inventories, Projections, and Opportunities for Reduction." EPA 430-R-99-01. with livestock contributing nearly 30% of anthropogenic methane emissions.H. Augenbraun Augenbraun, H., Matthews, E., & Sarma, D. (1997). "The Global Methane Cycle" Only 17% of these livestock emissions are due to manure management, with the majority resulting from enteric fermentation, or gases produced during digestion. With regards to antibiotic resistant bacteria, Staphylococcus Aureus accounts for 76% of bacteria grown within a swine CAFO. Group A Streptococci, and Fecal Coliforms were the two next most prevalent bacteria grown within the ambient air inside of swine CAFO.
