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Regulatory Information by Topic: Air

Under the Clean Air Act (CAA), EPA sets limits on certain air pollutants, including setting limits on how much can be in the air anywhere in the United States. The Clean Air Act also gives EPA the authority to limit emissions of air pollutants coming from sources like chemical plants, utilities, and steel mills. Individual states or tribes may have stronger air pollution laws, but they may not have weaker pollution limits than those set by EPA.

Read more at The Plain English Guide to the Clean Air Act

On this page:

Climate Change

See Cross-Cutting Issues: Climate Change

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Indoor Air

Indoor Air Quality: EPA does not regulate indoor air, but we do offer assistance in protecting your indoor air quality. Find information about mold, radon, formaldehyde and other indoor air quality issues.

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See Cross-Cutting Issues: Lead

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See Cross-Cutting Issues: Mercury

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Currently, there are no EPA regulations or standards for airborne mold contaminants. Learn more about mold on our Mold and Moisture site.

  • Policy and Guidance

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Congress designated EPA as the primary federal agency charged with protecting people and the environment from harmful and avoidable exposure to radiation. EPA responds to emergencies, assists in homeland security, assesses radiation risks, sets protective limits on emissions, and informs people about radiation and radiation hazards.

Wireless technology devices such as cell phones and computer networks are regulated by the US Federal Communication Commission (FCC) and the US Food and Drug Administration (FDA).  See: Wireless Technology.

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Stationary Sources

The Clean Air Act (CAA) requires major stationary sources to install pollution control equipment and to meet specific emissions limitations. In addition, under the 1990 CAA amendments, major stationary sources must obtain operating permits.

Acid Rain

Congress created the Acid Rain Program in Title IV of the 1990 Clean Air Act Amendments. The Acid Rain Program focuses on obtaining emission reductions of sulfur dioxide (SO2) and nitrogen oxides (NOx).

Read more from The Plain English Guide to the Clean Air Act: Reducing Acid Rain

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Common Air Pollutants

Carbon Monoxide, Ground-level Ozone, Lead, Nitrogen Oxides, Particulate Matter, and Sulfur Dioxide

The Clean Air Act (CAA) requires EPA to set National Ambient Air Quality Standards (NAAQS) for six common air pollutants. EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the standard. States are required to develop a general plan to attain and maintain the NAAQS in all areas of the country, and a specific plan to attain the standards for each area designated nonattainment for a NAAQS.

Read more from The Plain English Guide to the Clean Air Act: Cleaning Up Commonly Found Air Pollutants

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Cross State Air Pollution Rule (CSAPR)

See the Cross State Air Pollution Rule website.

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New Source Performance Standards (NSPS)

The Clean Air Act (CAA) requires EPA to create a list of the important categories of stationary sources of air pollution, and to establish Federal standards of performance for new sources within these categories. These New Source Performance Standards (NSPS) apply to newly constructed sources or those that undergo major upgrades or modifications. The standards include both equipment specifications as well as operation and measurement requirements.

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New Source Review (NSR)/Prevention of Significant Deterioration (PSD)

The Clean Air Act (CAA) requires all areas of the country to meet or strive to comply with the National Ambient Air Quality Standards (NAAQS). One of the key programs designed to achieve compliance with the NAAQS is the New Source Review (NSR) program, a preconstruction review process for new and modified stationary sources.

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Ozone Layer Protection

Under Title VI of the Clean Air Act (CAA), EPA is responsible for programs that protect the stratospheric ozone layer.

Read more at The Plain English Guide to the Clean Air Act: Protecting the Stratospheric Ozone Layer

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Operating Permits/Title V

Operating permits are legally enforceable documents that permitting authorities issue to air pollution sources after the source has begun to operate.

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Toxic Air Pollutants (Hazardous Air Pollutants)

The Clean Air Act (CAA) requires EPA to regulate emissions of toxic air pollutants from a published list of industrial sources referred to as "source categories." Toxic air pollutants include mercury, polychlorinated biphenyls (PCBs), benzene and volatile organic compounds (VOCs).

Read more at Plain English Guide to the Clean Air Act: Reducing Toxic Air Pollutants 

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Transportation: Mobile Sources

The Clean Air Act (CAA) mandates controls on air pollution from mobile sources by regulating both the composition of fuels and emission-control components on motor vehicles and nonroad engines. Vehicle fuel standards for gasoline and diesel are met by refiners/ importers, and by other parties in the fuel distribution system.

Regulation of vehicles includes vehicle emission limits for hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx), and particulates in the case of diesel vehicles. These limits, which must be met by the vehicle manufacturers, apply to on-road vehicles, off-road vehicles, and non-road sources (e.g., marine engines, locomotives, and lawn and garden equipment). Under the 1990 CAA amendments, vehicle standards are being made more stringent, in stages, through 2005 or later.

Read more at The Plain English Guide to the Clean Air Act: Cars, Trucks, Buses and “Nonroad” Equipment.

Vehicle safety information is available from the National Highway Traffic Safety Administration.

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On-road Vehicles and Engines Nonroad Vehicles and Engines Fuels and Fuel Additives

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One of the most basic forms of air pollution - haze - degrades visibility in many American cities and scenic areas. Since 1988 the federal government has been monitoring visibility in national parks and wilderness area.

Read more on the Visibility website .

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