Air Quality

The contributions of working landscapes to air quality are at best considered variable. Timberlands and, to a lesser extent, agricultural lands sequester large amounts of carbon by absorbing carbon dioxide, which traps heat in the atmosphere. However, working landscapes can emit substantial amounts of heat-trapping gases by burning fossil fuels to operate machinery, methane from cattle, and tilling soil releases a considerable amount of stored soil carbon into the atmosphere. In the production of food and fiber, modern working landscapes utilize great quantities of fossil fuels. A single irrigation pivot has the potential to release levels of nitrogen oxides comparable to more than 100 SUVs. Large quantities of animal waste from concentrated dairy and livestock operations also release large amounts of methane gas.

According to the State Air Resources Board, agricultural sources of air pollution account for more than fifty percent of the directly emitted particulate air pollution generated in the San Joaquin Valley during the fall season, amounting to over 170 tons per day of emissions.

Until recently, California state law had exempted agricultural sources from air pollution permit requirements. However, Title V of the federal Clean Air Act did not. Several public interest groups filed a suit against the U.S. Environmental Protection Agency for this discrepancy in 2001. The EPA settled the suit and required the state to establish a permit program for agricultural services or risk losing billions of dollars of federal money for highways.

In September 2003, Governor Gray Davis signed Senate Bill 700 into law, which repealed the agricultural source permit exemption. The bill has several key provisions. It defines "agricultural source" in state law; it removes the restriction from state law that prevented air districts from requiring permits for agricultural sources; and establishes specific permitting and exemption requirements for agricultural sources.

The law required the California Air Resources Board to adopt a definition for a large confined animal facility. Also, internal combustion engines, including portable and off-road engines used in agricultural operations, previously exempted, became subject to the new permitting process.

California’s local air quality district boards are required to adopt definitions and standards in order to implement all facets of the legislation by January 2007. California’s Air Resource Board maintains information about the rulemaking and implementation process regarding agricultural activities on its website.

As of July 2006, approximately 400 agricultural operations had applied for air permits in the San Joaquin Valley Air Pollution Control District, which includes some SOSA counties such as Madera, Fresno, and Tulare. Approximately 300 of the permits are for confined feeding operation, mostly dairies, and roughly 100 farms. The district anticipates significantly more applications once its recently adopted confined animal feeding rule, CAF Rule 4570, is implemented.