Section 231(a)(2)(A) of the Clean Air Act (“CAA”) provides that the Administrator of the United States Environmental Protection Agency (“EPA”) shall, from time to time, issue proposed emission standards for any air pollutants from any class of aircraft engine that, in her judgment, causes or contributes to air pollution that may reasonably be anticipated to endanger public health or welfare. On July 25, 2016, the Administrator issued a prepublication document finding that emissions of six greenhouse gases from certain classes of aircraft engines meet this standard (the “Finding”). The Finding paves the way for EPA to propose and promulgate aircraft emission standards applicable to emissions of relevant air pollutants from covered engines. The Finding neither sets emissions standard nor announces a timetable for doing so.


In a 5-4 decision, the Supreme Court held in Massachusetts v. EPA, 549 U.S. 497 (2007) that carbon dioxide and other greenhouse gases (“GHGs”) constitute “air pollutants” that can be regulated under the CAA. It further held that the Administrator bore a duty to determine whether emissions of GHGs from new motor vehicles cause or contribute to air pollution that may reasonably be anticipated to endanger public health and/or welfare.

Thereafter, EPA began to take a series of actions involving climate change regulation, including finding in 2009 that current and projected concentrations of the combined mix of six GHGs (CO2, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride) endanger public health and welfare (the “Endangerment Finding”). It also found that the combined mix of those GHGs from new motor vehicles or new motor vehicle engines contributes to the pollution that results in that endangerment. EPA subsequently issued emission standards for light-duty vehicles and heavy-duty engines and vehicles. From there, EPA turned to regulating carbon emissions from the power, energy and other sectors.

After Massachusetts v. EPA, environmental groups petitioned EPA to also make a finding that GHGs from aircraft engines satisfy Section 231(a)(2)(A). The petitioners want EPA to issue proposed standards for GHG emissions from aircraft engines and to promulgate final regulations quickly after doing so. The Finding responds to these petitions.

The Finding

EPA concludes that emissions from covered aircraft of the six GHGs subject to the Endangerment Finding contribute to air pollution that may reasonably be anticipated to endanger the public health and welfare of current and future generations. The Finding covers the following aircraft, to which the International Civil Aviation Organization (“ICAO”) agreed that a recently recommended global industry CO2 standard will apply: subsonic jet aircraft with a maximum takeoff mass greater than 5,700 kilograms and subsonic propeller-driven aircraft with a maximum takeoff mass greater than 8,618 kilograms. Examples of covered aircraft provided by EPA include smaller jet aircraft such as the Cessna Citation CJ3+ and the Embraer E170 up to and including the largest commercial jet aircraft—the Airbus A380 and the Boeing 747. Additional examples include larger turboprop aircraft such as the ATR 72 and the Bombadier Q400.

What Happens Next

The Finding will be effective 30 days after it is published in the Federal Register. The Finding is subject to judicial review by filing a petition in the US Court of Appeals for the District of Columbia Circuit within 60 days after publication. Petitions are likely to be filed based on issues raised by comments submitted after EPA proposed the Finding.

In the meantime, EPA expects to set a timeline for proposed GHG standards for covered aircraft as part of its Unified Agenda of Federal Regulatory and Deregulatory Actions, which is a semiannual compilation of information about regulations under development by federal agencies that is published in the spring and fall. While not an exhaustive list, EPA has stated that entities that will be interested in those standards include those that manufacture and sell aircraft engines and aircraft in the United States, including NAICS Codes 3364412 and 336411 and SIC Codes 3724 and 3721.

Future standards that may be promulgated by EPA will likely be affected by the development of international industry standards. EPA expects the ICAO to adopt a final emission standard for CO2 in March 2017. If an international standard is approved and finalized by ICAO, EPA will look to adopt standards that are of at least equivalent stringency as the ICAO standard.