The Clean Air Act gives primary responsibility for implementing our nation’s clean air programs to state and local air pollution control agencies.  In order for these agencies to work toward the goal of healthful air quality, they have to carry out a variety of programs and activities designed to reduce and limit air pollution.  For example, in order to plan their activities and determine their effectiveness, agencies must measure and predict the amount of pollution in the air.  State and local air agencies also must enforce the air quality rules and laws, train their staffs, issue permits to sources that may emit air contaminants and obtain the funding necessary to conduct these activities.



An important aspect of air quality control is measuring air pollution. This involves two types of measurements. First, air quality control agencies measure the ambient air to determine whether or not an area is meeting EPA’s health-based air quality standards. Ambient air monitoring is conducted via a network of monitors throughout the country that measure actual concentrations of various air pollutants, including sulfur dioxide, nitrogen dioxide, ozone, lead, particulate matter, carbon monoxide, and several toxic air pollutants.

Air quality agencies carry out enforcement and compliance programs to ensure that sources meet the applicable federal, state and local air pollution control requirements in their jurisdictions. There are several aspects of an agency’s enforcement and compliance program. EPA and state and local air agencies often provide compliance assistance to help the regulated community understand and comply with regulations.

All major facilities, ranging from power plants to refineries, are required under the Clean Air Act to obtain a permit. There are two main types of air pollution permits: preconstruction permits and operating permits. Sources must apply for preconstruction permits before building a new facility, or beginning major modifications to an existing facility, if the facility is expected to increase its emissions of regulated air pollutants by significant amounts.

State and local air quality officials receive training on air pollution from a number of training providers. EPA provides training to state and local air agencies via self-instructional courses, webinars and through classroom course materials (known as the Air Pollution Training Institute, APTI). Regional state organizations focusing on air quality issues develop and hold training courses, through classroom courses, workshops, conference and webinars.

State and local air pollution control programs in the United State are funded through a variety of sources. These include federal, state and local appropriations; the federal permit fee program under Title V of the Clean Air Act; state and local permit and emissions fee programs; and other funding programs that individual agencies operate.

The Clean Air Act allows state and local air pollution control agencies to adopt programs more stringent than those of the federal government.  In reality, most state agencies are still not able to adopt more stringent programs, due to state or local law, regulation, policy or other restrictions.  NACAA conducted a survey of state and local air agencies in September and October 2014 and discovered that over one-half of state respondents are precluded from adopting measures more stringent than federal requirements, or may do so only under special circumstances. Read Restrictions on the Stringency of State and Local Air Quality Programs (December 8, 2014) for details on the survey results.