US President Donald Trump has banned the use of sulfur compounds in acid rain and dust storms, a move that could make it easier to contain rising levels of carbon dioxide in the atmosphere.

The U.N. agency responsible for regulating air quality said on Friday that sulfur dioxide, a greenhouse gas, was banned in the United States as part of a nationwide effort to limit emissions of carbon monoxide and nitrogen dioxide.

The US Department of Energy said the new policy, which will be enforced by states, would save $1.2 billion in 2020 and $2.2 trillion over 20 years.

The EPA said the sulfur ban will protect people, property and the environment.

“It will reduce CO2 emissions from fossil fuels, reduce acid rain across the country, and reduce the amount of pollution that contributes to the buildup of ozone and other pollutants that are linked to asthma attacks and other health issues,” a EPA spokeswoman said.

“We are taking a leadership role in the fight against CO2, and our new sulfur ban is just one example of how we’re doing this.”

The agency has already banned sulfur compounds used in sulfur dioxide emissions, such as methyl tertiary butadiene and methyl tertium butadiine, from being used in air conditioners.

“The EPA is taking a lead role in reducing CO2 and helping our states and territories get a head start in tackling climate change,” said the EPA spokeswoman, Amy Stauffer.

The agency is considering how to make sulfur dioxide cleaner, which could include developing ways to capture or remove carbon dioxide from the air.

The announcement comes amid a global effort to curb carbon dioxide emissions linked to the burning of fossil fuels.

US President Trump has made climate change a top priority and has promised to use his powers as commander-in-chief to combat global warming.

The new rule is likely to be challenged in court.

The US Chamber of Commerce has already filed a brief in an ongoing legal challenge, saying it is unconstitutional.

The American Civil Liberties Union has called the ban an “attack on democracy”.US Secretary of State Rex Tillerson said on Thursday that he will seek approval from the Senate and House of Representatives before implementing the new EPA rule.

“If it is not approved, I think it will have a chilling effect on our ability to achieve and protect our climate, our environment and our citizens,” Tillerson said.

“We are not going to go ahead without the Senate.”

Tillerson said the US would also continue to use its existing programs to address the ozone hole, which the US Geological Survey said last year had grown by 40% in the past 20 years, and to try to cut carbon dioxide by 80% by 2030.