The United States safeguards public health and the quality of the natural environment by regulating air pollutants under the Clean Air Act and related laws.

Like many other environmental issues, public policies dealing with air pollution evolved from purely local or state jurisdiction in the early 20th century to a federal responsibility. A federal clean-air law was enacted in 1955, but major revisions in 1970 reflected growing environmental consciousness and established the government’s authority to set air standards nationwide and require the use of technology to improve air quality. Both the USDA and EPA work to set standards for air pollution. In 1998, the agencies established a Memorandum of Understanding (MOU) to share information and work collaboratively to promote clean air and agricultural productivity.

Operation: The Clean Air Act (CAA) can affect U.S. agriculture in a variety of ways, and the farm community has increasingly focused on these issues in recent years. Under the CAA, the government establishes National Ambient Air Quality Standards (NAAQS) that strive to protect public health from harmful levels of pollution. In parts of the United States that do not meet a NAAQS (called “non-attainment areas”), state and local governments develop and implement plans to reduce pollutants to acceptable levels. Among the pollutants regulated in this way is particulate matter (PM); the Environmental Protection Agency (EPA) has set standards for both “coarse” PM (particles 10 micrometers or less in diameter, or PM10) and “fine” PM (a diameter of 2.5 micrograms or less, PM2.5). Agricultural operations can be sources of PM10, although these emissions come from a wide variety of industries. As explained below, much current regulatory activity revolves around the development of methodologies that will allow accurate determinations of air emissions, which present major challenges in terms of measurement.

Two separate statutes deal with requirements to report some emissions, including airborne ones. The Emergency Planning and Community Right-to-Know Act (EPCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, or “Superfund”) were not enacted as agricultural laws, but they require reporting when threshold quantities of certain substances are released. Among these are ammonia and hydrogen sulfide, which are generated by animal manure. Discussion continues among regulators, Congress and the agricultural community on the appropriate application of CERCLA and EPCRA to agriculture.

Over the past decade, the government and the private sector have intensively studied the question of air emissions from agricultural operations, especially livestock, poultry and dairy farms. Measuring these emissions involves highly complex technical issues, and reliable nationwide, species-specific information has been scarce in the past. As part of an agreement with the Environmental Protection Agency (EPA), several animal agriculture sectors participated in a multi-year National Air Emissions Monitoring Study (NAEMS) to gather baseline emission data from farms in several representative geographic areas. That data is currently in use by the EPA to develop methodologies for producers to determine whether their operations met thresholds for reporting emissions.

Administration and Enforcement: The CAA is under the jurisdiction of the Environmental Protection Agency (EPA), an independent agency. As with the Clean Water Act, state agencies play an important role in carrying out the CAA’s requirements, establishing rules to bring their jurisdictions into compliance with federal rules. In fact, each state is required to establish a State Implementation Plan (SIP) to identify sources of air pollution and bring them into compliance with federal standards. These regulations on agricultural air emissions may vary from state to state, and producers are encouraged to keep up with changes in regulations and guidelines. The EPA also works closely with an Agricultural Air Quality Task Force established by the U.S. Department of Agriculture; the task force’s role is advisory and educational.

Statutory Authority: 42 U.S.C. 7401-7671; 42 U.S.C. 9601-9675; 42 U.S.C. 11001-11050