To find out which states require smog checks, visit DMV.org and click on a state to find out more information. For people that do live in states that require smog and emissions testing of vehicles, the DMV provides information on how to abide by the law. The DMV site also reveals whether smog testing is annual or biannual.
Smog checks are mandatory in many states and are strictly enforced, according to the DMV. A smog test can let the car owner know if the car is burning fuel efficiently, or if the car is required to get repairs to meet legal emissions standards. Smog testing contributes to the reduction of air pollution in states where it is implemented. Air pollution has a major impact on the health and well-being of citizens. For instance, California requires car owners to get annual smog tests on vehicles. The state's vigilance has paid off by removing a large amount of pollutants from the air that Californians breathe.
The requirements for smog testing varies from state to state, notes the DMV. Certain vehicles may be exempt from testing. Vehicle owners should consult state guidelines to see when to take a car in for a smog test.