EVERETT — The dread of driving a clunker to an emissions test — and maybe facing an expensive fix — is over.

After 38 years, Tuesday is the final day vehicles must be analyzed for carbon monoxide spewing from the exhaust pipe. The $15 tests were required in regions covering most of Clark, King, Pierce, Snohomish and Spokane counties. Failing a test meant getting exhaust system repairs, although that requirement was waived if the cost exceeded $150.

Stricter emission standards for new cars and trucks, enacted by the Legislature, took effect in 2008. Vehicles newer than the 2009 model year were excluded from testing, as were vehicles older than 25 years. The law created an ever-shrinking number of vehicles that were required to be tested.

At the height of Washington’s testing program in 2011, nearly 1.3 million vehicles got emissions checks. In 2017, just 12% of all licensed vehicles in the state were checked. Last year, about 750,000 tests were conducted.

“When we began the emission check program back in 1982, air pollution from carbon monoxide and ozone was a serious concern in many of our biggest cities,” said Kathy Taylor, manager of the Washington Department of Ecology air quality program, in a news release. “Today, new cars are much, much cleaner than in decades past, which means we can continue to improve our state’s air quality without these regular tests.”

Given the trend of cleaner engines and stricter emission requirements for new vehicles, the U.S. Environmental Protection Agency became convinced that air quality was not likely to deteriorate. Washington will continue monitoring air quality and must prove it will improve without emissions testing.

“If we see consistent high levels of air pollution, we are required under both the state and federal clean air acts to come up with a plan to reduce pollution and protect air quality,” said Andrew Wineke, a spokesman for the state Department of Ecology’s air quality program.

The end of emissions testing also means the end of a niche industry in Washington. About 180 people work for Applus, which operated testing stations, including in Everett, Marysville and Lynnwood. Another dozen Ecology employees will be affected by the program closing. The company and the state office worked with those employees to prepare for the shutdown.

When the EPA enacted air quality standards, it was to improve human health. Fine particulates, such as from forest fires, fossil fuel combustion or tree pollen, can aggravate respiratory and cardiovascular disease, reduce lung function and might be linked to lung cancer, according to the EPA.

“When we started the emission check program, parts of our state were threatened by high levels of carbon monoxide, ozone and particulate pollution — with levels sometimes above federal standards,” Wineke said. “Today, every part of Washington meets federal air quality standards.”

Washington’s emissions testing program started in 1982 with six test sites in King and Snohomish counties.

In 1980, the EPA’s air quality index included 11 days that were deemed unhealthy for sensitive groups and four days of air unhealthy for the whole population.

To date this year, Snohomish County has had 233 good days, 39 days with moderate air quality, one unhealthy day for sensitive groups and no generally unhealthy or very unhealthy days. The remaining days had particulate levels too small to measure.

A 1990 federal clean air law made emissions testing mandatory and resulted in the addition of testing facilities in 1993 for urbanized areas that weren’t meeting standards.

Starting in 2002, technicians plugged into a computer’s on-board diagnostics port to get a reading for most cars. That led to issues with Volkswagen vehicles equipped with 2- and 3-liter diesel engines that had emission-cheating devices which violated federal and state Clean Air Acts.

The settlement with the German auto company helped pay for electric buses in the Mukilteo, Snohomish and Stanwood-Camano school districts, and Everett Transit.

Washington’s climate won’t be affected much by the end of emissions testing. The program’s aim was to reduce toxics in the form of pollution like carbon monoxide, whereas carbon dioxide and other greenhouse gases are the primary drivers of climate change.

“Vehicles are still the largest source of carbon pollution in Washington — accounting for about 45% of our total emissions,” Wineke said.

Ben Watanabe: bwatanabe@heraldnet.com; 425-339-3037; Twitter @benwatanabe.