At a Glance

California has had its own standards since 1970.The state's governor called Trump's move a "pivotal moment" in the climate change debate.The dispute is likely headed to court.

President Donald Trump announced Wednesday that his administration is revoking California's right to set its own vehicle emissions standards, which are stricter than federal regulations.

Trump made the in a series of statements on Twitter. While he predicted that the move would bring down auto prices and encourage consumers to buy newer, safer and more fuel-efficient cars, critics said it was a setback in efforts to curb pollution and global warming, and an affront to states' rights.

Smog hangs over Los Angeles on June 11, 2019, a day rated as having "moderate" air quality downtown.

(Mario Tama/Getty Images)

California Gov. Gavin Newsom, a Democrat, and other top officials and environmental groups pledged to take the federal government to court to stop the move by Trump.

"You can't get serious about climate change unless you are serious about vehicle emissions," Newsom said, according to the Associated Press. "This is such a pivotal moment in the history of the climate change debate."

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A report from CalMatters earlier this year showed that in California had decreased 14 percent between 2004 and 2017. The report said vehicles are the primary source of greenhouse gases in the state, as they are nationwide.

This Feb. 14, 2019, photo released by Caltrans District 3 shows a 7-mile back up on southbound Interstate 5 as it reopens to traffic in Maxwell in Colusa County, California.

(Caltrans District 3 via AP)

Still, the three most polluted cities in the nation are in California, according to the American Lung Association's most recent report. Of 30 cities named on the report's three different "Top 10" lists, 17 are in California and the state topped every category. Los Angeles ranked first for the highest rate of ozone, the Fresno-Madera-Hanford metropolitan area had the highest year-round particle pollution and Bakersfield topped the list for short-term particle pollution.

, which is generated when sunlight reacts with pollutants from fossil fuels, such as emissions from cars, is the major component in smog, according the U.S. Environmental Protection Agency.

A waiver issued by Congress during passage of the Clean Air Act in 1970 granted California the authority to set its own, tougher emissions standards, the AP said. The state tried to impose the first-ever greenhouse gas limits on cars in the U.S. in 2007, when Republican Arnold Schwarzenegger was governor, but President George W. Bush's administration blocked the effort. The request was later granted under President Barack Obama.