The U.S. Environmental Protection Agency has not designated any areas of the country as having unhealthy air, missing an Oct. 1 deadline, according to the lawsuit. Such areas must take steps to improve their air quality.
Poor air quality particularly affects the health of children, people with asthma and those who work outside, said California Attorney General Xavier Becerra, who led and announced the filing. The lawsuit says smog can cause or aggravate diseases including heart disease, bronchitis and emphysema.
"Lives can be saved if the EPA implements these standards," he said in a statement.
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Becerra was joined by the attorneys general in Connecticut, Illinois, Iowa, Maine, Maryland, Massachusetts, New York, Oregon, Pennsylvania, Rhode Island, Vermont and Washington state. Minnesota's Pollution Control Agency also joined the suit.
The EPA said the agency's policy is not to comment on litigation.
The suit is the latest allegation by Democratic officials in California and other states that the Trump administration is illegally delaying environmental actions as it attempts to unwind rules set under former President Barack Obama.
Becerra, for instance, noted that he previously sued Trump officials for what he calls an illegal delay of a rule encouraging automakers to create vehicle fleets that meet or exceed federal fuel efficiency standards.
Clean Air Act standards require that smog-producing ground-level ozone be kept below levels the federal government decides won't affect public health. The lawsuit says the EPA missed its deadline to say which regions are not meeting the most recent standards set by the Obama administration in 2015.
The EPA determined, in setting the ozone standards, that the required reductions would produce billions of dollars' worth of health benefits annually despite the costs of complying.
Failing to designate regions who are not complying deprives state and local regulators of crucial regulatory tools not otherwise available, according to the lawsuit. States were required under the law to recommend which areas they believe are not meeting the standards.
Nationwide, the tighter restrictions were projected to save between 316 and 660 lives each year, prevent nearly 900 hospital visits and keep children from missing 160,000 school days, bringing $4.5 billion in health benefits. That includes up to 218 saved lives and $1.3 billion in savings in California alone from a reduction in health care costs, lost workdays and school absences, according to the lawsuit.
The EPA tried in June to extend its deadline to Oct. 1, 2018, but then withdrew the proposed extension in the face of lawsuits from states and advocacy groups.
Last month, it designated some areas as meeting standards but said it was postponing any decisions on regions that weren't complying, including densely populated and high-risk urban areas, until "a separate future action," the suit says. The agency didn't say when it would act.
Efforts by states and regional air districts to reduce emissions from motor vehicles and other sources will be more difficult as the climate warms, California Air Resources Board Executive Officer Richard Corey said.
He said the EPA has had the information it needs to make the required designations for months without acting. The lawsuit asks a judge to order the EPA to act promptly.
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