The Clean Air Act Amendments of 1990 is a federal law that sets limits on how much pollution is allowed in the air anywhere in the United States. The goal is to make sure that all Americans have clean, healthy air to breathe. EPA can fine violators who break the law and put too much pollution into the air.

Parts of the Clean Air Act Amendments, called “Titles,” established permit programs to limit the amount of pollutants that sources such as factories, industries, and vehicles can release. These permits are issued by states or EPA and include information on which pollutants are being released, how much may be released, and what steps are being taken to reduce the pollution. Sources of pollution have to pay for the permits, and the money from the fees helps support state air pollution control activities.

In addition, the Clean Air Act Amendments established a specific program to reduce the pollutants that cause acid rain—sulfur dioxide and nitrogen oxides. This program—the Acid Rain Program—uses allowances to control the amount of pollution that a source can produce. Each source can decide if it wants to buy, sell, or save these allowances. There are stiff penalties, however, for sources that release more pollutants than their allowances cover. As of 2001, the Acid Rain Program had reduced sulfur dioxide emissions by 33 percent and nitrogen oxide emissions by 27 percent. For more information, see the Plain English Guide to the Clean Air Act.