The 1990 Clean Air Act is a piece of United States environmental policy relating to the reduction of smog and air pollution. Although the Clean Air Act is a federal law covering the entire country, the states do much of the work to carry out the Act. Auto inspections were included in the law to make sure cars are well maintained. When your register a car in California, an emissions check is required, and with every other registration renewal the check must be done again. Used car dealers are required to issue a valid emissions test for any vehicle they sell. With a private sale it is the responsibility of the buyer.

Dozens of auto repair shops and service stations in New York City, Long Island and Westchester County faked the results of emissions tests, giving nearly 21,000 cars and light trucks passing grades, state environmental officials said Thursday. Officials with the State Department of Environmental Conservation said they had issued citations to 40 of about 3,500 inspection sites in the region for granting inspection certificates for vehicles that were not tested. These stations could face fines of $375 to $15,000 for the first offense and up to $22,500 for each ensuing offense. Although the emissions testing costs only about $37, repairs to vehicles that fail the test can cost much more. Dealerships may pass a vehicles emission test to save on money, leaving the consumer to have to pay for the repairs when they take their vehicle for the next emissions test.