The Environmental Protection Agency on Monday took a key step toward limiting pollution caused by the nation’s fleet of commercial aircraft, part of a broader push in the Obama administration’s waning months to reduce U.S. greenhouse gas emissions.

The EPA issued a scientific assessment known as an “endangerment finding,” which determined that emissions from certain kinds of plane engines contribute to pollution that fuels climate change and creates health risks for Americans. Emissions that include carbon dioxide, methane, nitrous oxide and other compounds come primarily from engines used on large, commercial jets, the agency said.

“If you look at the challenge of greenhouse gases, we really need to look at every sector to identify where there are opportunities,” EPA Administrator Gina McCarthy said in an interview. “The good news about the opportunities in the aircraft sector is that it relates to aircraft becoming more efficient. It relates to aircraft engines that will produce less pollution — not just greenhouse gases, but less [nitrous oxide] pollution and potentially noise pollution.”

Monday’s determination is merely one step in what could be a years-long undertaking to adopt domestic emissions standards on aircraft engines. It puts in place a framework for U.S. regulators to partner with the International Civil Aviation Organization to set global CO2 emissions standards next year. The EPA said Monday that it “anticipates moving forward on standards that would be at least as stringent as ICAO’s standards.”

Of course, that effort could depend on the outcome of the fall presidential election. While presumptive Democratic nominee Hillary Clinton has vowed to carry on and even expand President Obama’s climate-related agenda, Republican nominee Donald Trump has vowed to dismantle the EPA and has questioned the science behind climate change.

According to the EPA, commercial aircraft contribute roughly 11 percent of emissions from the U.S. transportation sector and about 3 percent of all U.S. emissions. That is relatively small when compared to cars or power plants. But car emissions already are regulated, and the Obama administration has made a major push to rein in emissions from power plants under the proposed Clean Power Plan.

While environmental groups have supported curbs on airline emissions, some have worried the standards set by an international body might prove too weak. They have long pushed the EPA to go further.

The Center for Biological Diversity and Friends of the Earth, represented by the environmental law group Earthjustice, petitioned the EPA in 2007 to regulate carbon emissions from aircraft under the federal Clean Air Act. In 2010, the groups sued to compel regulators to set standards on greenhouse-gas pollution from planes.

“EPA’s finding today confirms that aircraft emissions are significant and need to be regulated,” Dan Rutherford, aviation program director for the nonprofit International Council on Clean Transportation, said in a statement. Rutherford said research suggests new aircraft designs could cut fuel usage by nearly a quarter by 2024, far more than would be required by the current international proposal. “Manufacturers can do more, and U.S. policies should reflect that.”