The Biden administration is proposing to require that future airplanes produce lower levels of greenhouse gas emissions before they can be certified.

The Federal Aviation Administration said on Wednesday that its proposal would cover planes under development, including two Boeing models and one from Airbus. It would also apply to planes built after Jan. 1, 2028. Planes are a small but growing contributor to greenhouse gas emissions.

The FAA says civilian planes caused 3% of U.S. emissions before the pandemic.

It marks a step forward as Environmentalists have tried for years to get the government to regulate the amount of heat-trapping emissions that planes put out.

In 2015, the Environmental Protection Agency found that aircraft emissions posed a health threat. That discovery required the FAA to draft rules. In 2020 the Trump administration announced a proposal that critics alleged would do little more than approve steps the aviation industry had already committed to take.