Update: Some of the source articles are no longer available.
Getting your car checked for excessive emissions has been a part of the American driving experience since 1966, when California launched the first vehicle emissions testing program. However, emissions testing has never been required for everyone. As of 2017, 32 states have some form of emissions testing, but most require testing only in specific regions. Other states have no emissions testing at all.
Understanding the roles that the federal and state governments have in ensuring air pollution is kept to a minimum makes it more clear why some places have emissions tests while others don't.
If you live in a region where emissions tests are required, you have to bring your car to a testing station once a year, or once every other year, to ensure that it's producing minimal levels of pollutants. If your vehicle fails an emissions test you are required to have the car repaired.
How states differ
In some states emissions testing is state-wide, like Massachusetts, which requires vehicles to have an emissions test as part of an annual safety inspection for a fee. The majority of other states, like California, Nevada and Missouri, require emissions testing only in specific regions, usually in more densely populated areas and usually every two years. Other states, like Florida, Montana and Nebraska require no emissions testing.
Federal laws and the EPA
While the federal government's Clean Air Act stipulates air quality levels for the entire country, how these targets are achieved is left up to each state.
The federal Clean Air Act, enforced by the EPA, specifies the maximum levels of pollutants allowable in the air for chemicals and elements like carbon monoxide, lead, ozone and sulfur dioxide. These levels are usually measured in parts per million, or ppm. If a state were to exceed these levels that state would be responsible for creating a plan to correct it, and not the EPA. If state legislatures believed cars were contributing to the problem, they could enact emissions testing. However, if they felt local manufacturing was to blame they might impose restrictions on that industry instead. In any event, the decision is always up to the state government.
Why some states don't require emissions testing
In the 1990s Florida did require emissions testing in metropolitan areas like Miami, Tampa and Jacksonville; later, however, the state government eliminated them. While the cut wasn't without controversy, the government believed the tests were not necessary since the state was meeting federal air quality standards, and estimated the cost savings to taxpayers to be up to $50 million each year.
While at the time of publication emissions testing is required in six counties in Tennessee, the state government began making moves away from these tests in 2016. The Tennessee senate voted to end emissions testing in that state. The $9 annual test required was described as an annoyance to drivers by some lawmakers. Some also cited a recent Volkswagen scandal as a reason to eliminate the tests, as the auto manufacturer had installed software in some vehicles to cheat emissions tests.
- EPA: The Plain English Guide to the Clean Air Act
- EPA: NAAQS Table
- NBC 2: Good Question: Why Doesn't Florida Require Vehicle Inspections
- St Petersburg Times: Bill Ends Exhaust Tests
- Memphis Daily News: Tennessee Senate Votes to End Emissions Tests for New Cars
- LA Times: Six High-Level Volkswagen Employees Indicted in Emissions Scandal
- Tennessee Department of Environment & Conservation: Emissions Testing Information and Station Schedules - See more at: https://www.tn.gov/environment/article/apc-emissions-testing-information-and-station-schedules#sthash.JLxQDkHM.dpuf
- AAA: Emissions Inspection