"From an environmental quality standpoint, much of the public and policy interest in animal agriculture has focused on impacts on water resources, because animal waste, if not properly managed, can harm water quality through surface runoff, direct discharges, spills, and leaching into soil and groundwater. A more recent issue is the contribution of air emissions from animal feeding operations (AFOs), enterprises where animals are raised in confinement. This report provides background on the latter issue. AFOs can affect air quality through emissions of gases such as ammonia and hydrogen sulfide, particulate matter, volatile organic compounds, hazardous air pollutants, and odor. These pollutants and compounds have a number of environmental and human health effects. Agricultural operations have been treated differently from other businesses under numerous federal and state laws. Some environmental laws specifically exempt agriculture from regulatory provisions, and some are designed so that farms are not subject to most, if not all, of the regulatory impact. The primary regulatory focus on environmental impacts has occurred under the Clean Water Act. In addition, AFOs that emit large quantities of air pollutants may be subject to Clean Air Act regulation. Some livestock operations also may be regulated under the release reporting requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Emergency Planning and Community Right-to-Know Act (EPCRA). Questions about the applicability of these laws to livestock and poultry operations have been controversial and have drawn congressional attention. Agriculture's role as both a source of and a 'sink' for greenhouse gases also has been of interest in connection with addressing the global challenge of climate change."
CRS Report for Congress, RL32948
National Agricultural Law Center: http://nationalaglawcenter.org/