With a legal eye on the skies, the Environmental Protection Agency (EPA) said on Monday they are finalizing the first-ever emissions guidelines for airplanes that regulate greenhouse gas (GHG) emissions.

The new airplane emissions standards will be mandatory for commercial aviation and any large business jets. Under the new emissions guidelines, the US will fall into lockstep with international standards already established across the globe.

“This standard is the first time the US has ever proposed regulating greenhouse gas emissions from aircraft,” said EPA Administrator Andrew Wheeler. “Along with the Affordable Clean Energy and Safer Affordable Fuel-Efficient Vehicle rule, this is the Trump Administration’s third major action to take sensible, legally defendable steps to regulate greenhouse gases, while safeguarding American jobs and the economy.”

In 2016, the new standards were triggered by the Clean Air Act when the EPA reported emissions of GHGs from aircraft engines caused or contributed to air pollution.

The EPA released a statement about the new International Civil Aviation Organization (ICAO) standards, recognizing “significant input from EPA, the Federal Aviation Administration (FAA), and US and international aviation industries.”

It is expected the new standards will positively impact US airplane manufacturers, such as Boeing, due to the global market. The EPA reports that “three out of four aircraft manufactured in the US are sold overseas. These standards will help ensure consistent standards across the world, and most importantly allow US manufactured planes, such as commercial and large passenger jets, to continue to compete in the global marketplace.”

Boeing released a statement calling the new emissions standards “vital for protecting the environment and supporting the sustainable growth of commercial aviation and the United States economy.”

However, numerous states and environmental experts are critical of the new standards, which they find weak, especially during the ongoing climate crisis.

Eleven states led by California and the District of Columbia reached out to the EPA in October with an urgent plea to tighten the new standards before approving them. In their request, they said that if passed as currently written, the proposal will "lag existing technology by more than ten years and would result in no GHG reductions at all compared to business-as-usual."

Annie Petsonk, counsel for the Environmental Defense Fund, agreed with the states' critique of the proposed new emissions standards.

Referring to the EPA’s new emissions rules under review, Petsonk said the "do-nothing rule is totally inadequate in light of the climate crisis. It’s incumbent on the incoming Biden-Harris administration to move swiftly to tighten this standard.”

EPA Administrator Andrew Wheeler previously said the proposal can only be based on "where the technology is today ... You can't really set the standard that can't be met.”

The proposed new airplane standards will impact about ten percent of all US transportation greenhouse emissions and three percent of total US emissions. To date, airplanes have been the largest root cause of greenhouse gas emissions not regulated.

The EPA said that starting in January 2020, the new requirements will apply to new airplane designs as well, but for those in production or any with amended certificates, the new rules would take effect starting in 2028.

As far as compliance, the EPA said they believe it is a non-issue. The organization expects "airplanes that are non-compliant will either be modified and re-certificated as compliant, will likely go out of production before the production compliance date of January 1, 2028, or will seek exemptions.”