About EPA

Highlights of the 1990 Clean Air Act Amendments

[EPA Journal - January/February 1991]

Urban Pollution

Cities currently failing to meet standards for human health must "attain" them by deadlines set in the law: Most have 6 years or less or attain; an extreme case, Los Angeles, has 20 years. State programs for these cities will complement EPA efforts; see Motor Vehicles.

  • Ozone. The 96 cities failing for ozone are ranked from marginal to extreme, with the more severe cases required to institute more rigorous controls, but given more time to attain. States may have to initiate or upgrade inspection/maintenance (I/M) programs; install vapor recovery at gas stations and otherwise reduce hydrocarbon emissions from small stationary sources; and adopt transportation controls that will offset growth in vehicle miles travelled. Major stationary sources of nitrogen oxides will have to reduce emissions.

  • Carbon Monoxide. The 41 cities failing for carbon monoxide are ranked moderate or serious; states may have to initiate or upgrade I/M and adopt transportation controls.

  • Particulate Matter. The 72 areas failing to attain for particulate matter (PM-10) are ranked moderate; states will have to implement Reasonably Available Control Technology (RACT); use of wood stoves and fireplaces may have to be curtailed.


The new act strengthens the ability of EPA and the states to enforce standards by requiring that all air-pollution-control obligations of an individual source be contained in a single five-year operating permit. The states have three years to develop permit programs and submit them to EPA. EPA has one year to issue regulations describing the minimum requirements for such programs. Sources must pay permit fees to the states to cover the costs of operating the programs.

Motor Vehicles

  • Vehicle Emissions. Tailpipe emissions of hydrocarbons, carbon monoxide, and nitrogen oxides will be cut beginning with the 1994 model year, and standards will have to be maintained over a longer vehicle life. On-board charcoal cannisters to absorb evaporative emissions may be required.

  • Fuels. In 1995, reformulated gasolines having less aromatics will be introduced in the nine cities with the worst ozone problems; other cities can "opt in." Beginning in 1992, oxyfuels gasolines blended with alcohol will be sold in winter in those cities having the worst carbon monoxide problems.

  • Clean Cars. In 1996, a pilot program will introduce 150,000 cars to California that meet tighter emission limits through a combination of vehicle technology and "clean" fuels - substitutes for gasoline or blends of substitutes with gasoline. Other states can "opt in."

Air Toxics

Emissions of 189 toxic pollutants, typically carcinogens, mutagens, and reproductive toxins, must be reduced within 10 years. EPA will publish a list of source categories within one year and issue Maximum Achievable Control Standards (MACT) for each category over a specified timetable. Companies that initiate partial controls before the deadlines set for MACT can receive extensions.

Acid Rain

A two-phase, market-based system will reduce sulfur-dioxide emissions from power plants by more than half. By the year 2000, total annual emissions are to be capped at 8.9 million tons, a reductions of 10 million tons from 1980 levels. Plants will be issued allowances based on fixed emission rates set in the law and on their previous fossil-fuel use. They will pay penalties if emissions exceed the allowances they hold. Allowances can be banked or traded. In Phase I, large, high-emission plants, located in eastern and midwestern states, will achieve reductions by 1995. In Phase II, which commences on January 1, 2000, emission limits will be imposed on smaller, cleaner plants and tightened on Phase I plants. All sources will install continuous emission monitors to assure compliance. Nitrogen-oxide reductions will also be achieved, but through performance standards set by EPA.

Ozone Depletion

The new act goes beyond the Montreal Protocol in restricting use, emissions, and disposal of chemicals. It phases out production of CFCs, carbon tetrachloride, and methyl chloride by 2000; and methyl chloroform by 2002; it freezes production of CFCs in 2015, phasing them out in 2030. Companies servicing air conditioning for cars will be required to purchase certified recycling equipment and train employees by January 1, 1992. By July, EPA regulations must require reduced emissions from all other refrigeration sectors to lowest achievable levels. By November 1992, use of CFCs in "nonessential" applications will be prohibited. The act mandates warning labels on all containers and products (refrigerators, foam insulation) that enclose CFCs and other ozone-depleting chemicals.