Clean Air Act (1990)

The 1990 Clean Air Act is a piece of United States environmental policy relating to the reduction of smog and air pollution. It follows the Clean Air Act in 1963, the Clean Air Act Amendment in 1966, the Clean Air Act Extension in 1970, and the Clean Air Act Amendments in 1977. It was enacted by the 101st United States Congress ().

The roles of the federal government and states

Although the 1990 Clean Air Act is a federal law covering the entire country, the states do much of the work to carry out the Act. For example, a state air pollution agency holds a hearing on a permit application by a power or chemical plant or fines a company for violating air pollution limits.

Under this law, the EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. States are not allowed to have weaker pollution controls than those set for the whole country.

The law recognizes that states should lead in carrying out the Clean Air Act, because pollution control problems often require special understanding of local industries, geography, housing patterns, etc.

States must develop state implementation plans (SIPs) that explain how each state enforces the Clean Air Act. A state implementation plan is a collection of the regulations a state will use to clean up polluted areas. The states are obligated to notify the public of these plans, through hearings that offer opportunities to comment, in the development of each state implementation plan.

EPA must approve each SIP, and if an SIP isn't acceptable, EPA can take over enforcing the Clean Air Act in that state.

The United States government, through EPA, assists the states by providing scientific research, expert studies, engineering designs and money to support clean air programs.

National permits program

State environmental agencies issue air permits to large stationary sources of pollution such as power plants and factories. The permitting process requires a monitoring plan to be created and sets limits on the amounts and types of releases allowed. The information contained in this permit is made available to both the polluter, other agencies, and the public.

These permits are known as ‘part 70’ permits because they are related to the federal requirements in 40 CFR part 70. These permits are also known as ‘title V’ permits because they are required by Title V of the 1990 Clean Air Act. The title V permit is meant to contain all the requirements for emissions from the permitted source. The permit requires reporting, monitoring, and annual certification of compliance, all of which is public information.

The permit information is available online through the EPA ECHO (Enforcement and Compliance History Online) database and the permits themselves are available online through the websites of various state agencies or EPA regional offices.

Interstate air pollution

Air pollution often travels from its source in one state to another state. In many metropolitan areas, people live in one state and work or shop in another; air pollution from cars and trucks may spread throughout the interstate area. The 1990 Clean Air Act provides for interstate commissions on air pollution control, which are to develop regional strategies for cleaning up air pollution. The 1990 Clean Air Act includes other provisions to reduce interstate air pollution.

The Acid Rain program, created under Title IV of the Act, authorizes emissions trading to reduce the overall cost of controlling emissions of sulfur dioxide.

Mobile Source Pollution

The Clean Air Act requires the federal government (meaning the EPA) to set limits on air pollutants emitted from the tailpipes of new motor vehicles. California is the only state allowed to deviate from the standards set by the federal government, and it is only allowed to do so if its standards are at least as protective of human health as the federal standards, and it obtains a waiver from the EPA. Other states have the choice of adopting the federal standards or the California standards.

The Clean Air Act requires that States with heavy air pollution use oxygenated gasoline. This is known as the "Clean Fuel Requirement" because oxygenated gasoline produces less air pollution than regular gasoline for older vehicles which use a carburetor. It is often wrongly thought that newer vehicles, which use fuel injection and closed loop fuel control, also benefit from the use of oxygenated fuels. However, this is simply not the case.

International air pollution

Air pollution moves across national borders. The 1990 law covers pollution that originates in Mexico and Canada and drifts into the United States and pollution from the United States that reaches Canada and Mexico.

Leak detection and repair

The Act requires industrial facilities to implement a Leak Detection and Repair (LDAR) program to monitor and audit a facility's fugitive emissions of volatile organic compounds (VOC).

The program is intended to identify and repair components such as valves, pumps, compressors, flanges, connectors and other components that may be leaking. These components are the main source of the fugitive VOC emissions.

Testing is done manually using a portable vapor analyzer that read in parts per million (ppm). Monitoring frequency, and the leak threshold, is determined by various factors such as the type of component being tested and the chemical running through the line. Moving components such as pumps and agitators are monitored more frequently than non-moving components such as flanges and screwed connectors. The regulations require that when a leak is detected the component be repaired within a set amount of days. Most facilities get 5 days for an initial repair attempt with no more than 15 days for a complete repair. Allowances for delaying the repairs beyond the allowed time are made for some components where repairing the component requires shutting process equipment down.