Ozone is created from a mixture of car exhaust, other air emissions and intense sunlight. High levels of ozone can cause health and breathing problems for some people.

It will be at least another year before federal officials take the first step toward pushing Tucson to reduce its ozone levels — if that happens at all.

The U.S. Environmental Protection Agency is reviewing whether to raise or lower the federal air quality standards for ozone — standards that Pima County now appears to be violating.

Once that’s done, Pima County officials expect the EPA will determine if the county is actually in a legal state of noncompliance with the standards.

“The public can expect to see a proposed decision by early 2020,” said agency spokesperson Michael Abboud about revising the current ozone standard of 70 parts per billion. A final decision is due at the end of 2020, the EPA said.

Ursula Nelson, director of the Pima County Department of Environmental Quality, said she doesn’t expect the EPA to act on Tucson’s ozone violations until it settles on new standards.

She also isn’t optimistic that the EPA will meet its early 2020 goal for proposing new standards. “Historically, EPA has not been timely with their reviews,” she said.

The EPA last tightened its ozone standard in 2015, when it reduced maximum ozone levels in the air from 75 to 70 parts per billion.

At the time, some business groups criticized the new standard as unrealistically harsh while some environmental groups and scientists said it wasn’t tough enough.

Pima County officials learned the county’s air is violating the current standard last year.

Last summer, the Tucson area exceeded the standard on four days, pushing the area into noncompliance for 2016 to 2018.

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A little more has recently happened at the state level toward cleaning up the air.

The Arizona Department of Environmental Quality launched a program last year aimed at reducing vehicle emissions by paying residents to fix older vehicles that fail emissions tests.

The program pays up to $550 to owners of gasoline-powered vehicles and up to $1,000 to owners of diesel-powered vehicles 12 years and older. Owners must pony up the first $150 toward the repair tab to get the rest.

The program, however, is geared more toward helping motorists pass tests for hydrocarbons and carbon monoxide, neither of which occurs in ozone.

And in February 2019, the Arizona Corporation Commission renewed a ban keeping state-regulated power companies from investing in new natural-gas power plants as a way of limiting greenhouse gases that can push up temperatures and ozone pollution.

Contact reporter Tony Davis at tdavis@tucson.com or 806-7746. On Twitter@tonydavis987