Smog check, smog test and emission check all refer to the same thing: a test of vehicle and its engine emissions performed at a licensed smog testing facility.
Smog checks are regulated by the U.S. Environmental Protection Agency (EPA), whose goal is to protect public health and the environment from the dangerous effects of air pollution. In 1990, the Clean Air Act gave the EPA its authority to oversee states with respect to emissions.
California is the only state that is allowed to adopt its own emissions standards and these are the toughest standards in the nation. Other states can either implement the Federal or the California emissions standards. Thirty-one states require emissions testing or smog checks. Some states, such as Florida and Minnesota, used to require smog checks but have eliminated them (Florida in 2000, Minnesota in 1999).
Most states require vehicle emissions testing every two years, but not every vehicle requires a smog check. In California, for example, whether or not a smog check is required depends on the type of vehicle, the model year, and the area in which the vehicle is registered. Vehicles that are six or less model years old are not required to have the biennial smog check.
In New York, like California, registration renewal notices mailed to owners contain a warning message if there’s no record of a valid emissions and regular safety inspection on file (inspections are required annually). Vehicles exempt from the emissions inspection program are those that are less than two years old, 26 model years old or older, registered with historic plates, or are electric-powered only.
California law requires a smog check if the vehicle registration renewal notice says “Smog Certification Required,” if the vehicle is being sold, or if the vehicle is being brought into California to be registered.
The best way to determine if your state, city or county requires a smog check is to go to your state DMV website.