The Biden administration is restoring California’s authority to set its own automobile tailpipe pollution standards, reversing a Trump administration policy and likely ushering in stricter emissions standards for new passenger vehicles nationwide.

A waiver approved by the Environmental Protection Agency on Wednesday allows California to impose mandates for so-called zero-emission vehicles that do not contribute to global warming.

At least 15 states and the District of Columbia have agreed to California’s vehicle standards, which are stricter than federal regulations and are intended to address the state’s severe air pollution issues. According to the American Lung Association, seven of the ten worst ozone polluted cities in the United States are in California, as are six of the ten most polluted cities in terms of year-round particle pollution.

Former President Donald Trump’s decision in 2019 to revoke California’s authority to set its own limits on auto emissions was one of his most high-profile actions to roll back environmental regulations that he saw as too burdensome on businesses. Vehicle emissions regulation is critical to combating climate change.

Slowing climate change is a top priority for President Joe Biden’s administration. Transportation is the single largest source of greenhouse gas emissions in the United States, accounting for 29 percent of total emissions. Passenger cars and trucks are the largest contributors in the transportation sector, accounting for 58 percent of all transportation-related emissions and 17 percent of total U.S. carbon emissions.

“Today, we proudly reaffirm California’s longstanding authority to lead in addressing car and truck pollution,” said EPA Administrator Michael Regan. “With today’s action, we reintroduce an approach that has for years aided in the advancement of clean technologies and the reduction of air pollution for people not just in California, but across the country.”

The waiver, which is effective immediately, restores California’s authority to regulate greenhouse gas emissions under the federal Clean Air Act for model years 2017 through 2025. The California Air Resources Board will decide how the standards will be implemented and enforced.

The waiver also removes a Trump-era regulation that prevented other states from adopting California’s standards. They collectively account for 36% of the US auto market.

California, New York, and other states have asked for the waiver to be reinstated, claiming that the state’s strict standards have improved air quality and ensured that Los Angeles and other cities are no longer shrouded in smog.

California Attorney General Rob Bonta called the state’s vehicle-emissions standards “critical to the fight against climate change” and “critical to improving air quality, protecting public health, and driving technological innovation” at a public hearing last year. The EPA’s decision to reinstate California’s standards “is a victory for public health, the legal authority of the Clean Air Act, and states’ rights,” said Harold Winner, president and CEO of the American Lung Association.

The new bipartisan infrastructure bill includes 500,000 new electric vehicle charging stations. Fully electric vehicles, or EVs, account for only 2% of new vehicle sales in the United States, but analysts anticipate a rapid increase in the coming years. Major automakers, such as General Motors and Ford, have pledged billions of dollars to develop EVs, with GM going so far as to announce a goal of eliminating gasoline-powered passenger vehicles entirely by 2035. Starting with the 2023 model year, the EPA rule raises mileage standards, with an industry-wide target of 40 miles per gallon by 2026. The new standard is 25% higher than the Trump administration’s final rule and 5% higher than an earlier proposal by the Biden EPA.

Trump’s decision to revoke the state waivers divided the industry, with most automakers supporting him and Ford, Honda, BMW, Volkswagen, and Volvo opting for California standards. Following Biden’s election, General Motors and other automakers advocated for California to set its own standards.

The reintroduction of the California waiver comes as the Biden administration proposes tougher pollution regulations for new tractor-trailer rigs, which would clean up smoky diesel engines and encourage new technologies over the next two decades. The EPA proposed on Monday that the industry reduce smog- and soot-forming nitrogen oxide emissions by up to 90 percent per truck by 2031, compared to current standards. Humans may experience respiratory problems as a result of the emissions.