The U.S. Environmental Protection Agency is planning to propose new rules to limit greenhouse gas emissions from airplanes.

The EPA will release in the coming days its “endangerment finding,” concluding that airplane emissions are harmful to human health, reports the New York Times. Release of the EPA’s endangerment finding will trigger the rule-making process.

According to the EPA, airplanes produce 3 percent of the nation’s total greenhouse gas emissions and 11 percent of the U.S. transportation sector’s emissions.

The expected move to propose airplane emission standards follows regulatory action the Obama administration has taken to curb carbon pollution from vehicles and power plants. The regulatory measures, applauded by environmentalists, have been met with push back from Republicans and other opponents. 

William Becker, executive director of the National Association of Clean Air Agencies, said he is encouraged that the EPA is expected to propose limits on airplane emissions. 

“Aircraft are the largest remaining unregulated source of greenhouse gas emissions from the transportation sector and can only be regulated by the federal government,” he told the Times. “This presents President Obama with a tremendous opportunity to demonstrate leadership not only domestically but, indeed, around the world.”