The Obama Administration is making findings that greenhouse gas (GHG) from aircraft endanger the public health and welfare of current and future generations within the meaning of section 231(a) of the Clean Air Act. The findings specifically refer to six greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. These gases were previously defined as air pollution in the 2009 Endangerment Finding under section 202(a) of the Clean Air Act.
If EPA issues final findings that greenhouse gas emissions from engines used in certain aircraft cause or contribute to air pollution that endangers public health or welfare, then EPA would have a duty under section 231 of the Clean Air Act to promulgate applicable aircraft engine emission standards. Those standards would apply to entities that manufacture and sell new aircraft engines and new aircraft in the United States.
Covered aircraft would include: subsonic jet aircraft with a maximum takeoff mass (MTOM) greater than 5,700 kilograms, and subsonic propeller-driven (e.g., turboprop) aircraft with a MTOM greater than 8,618 kilograms. Examples of covered aircraft would include smaller jet aircraft such as the Cessna Citation CJ2+ and the Embraer E170, up to and including the largest commercial jet aircraft—the Airbus A380 and the Boeing 747. Other examples of covered aircraft would include larger turboprop aircraft, such as the ATR 72 and the Bombardier Q400.
The proposed findings are in response to a citizen petition submitted by Friends of the Earth, Oceana, the Center for Biological Diversity, and Earthjustice requesting that EPA issue an endangerment finding and standards under section 231(a)(2)(A) of the Act for the GHG emissions from aircraft.
EPA anticipates that the International Civil Aviation Organization (ICAO) will adopt a final CO2 emissions standard in February 2016. EPA’s current proposal is in anticipation of a subsequent rulemaking process in the United States to adopt standards that are of at least as stringent as the anticipated ICAO CO2 standards.
Greenhouse gases in the atmosphere (both naturally occurring and anthropogenic) are thought to trap some of the Earth’s heat that would otherwise escape to space. Some GHGs are associated with human activities, including CO2, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Of these six gases, two (CO2 and nitrous oxide) are emitted by aircraft engine.
Before the Administrator can issue GHG emission standards under CAA section 231, the Administrator must first decide whether the air pollution may reasonably be anticipated to endanger public health or welfare. Then the Administrator must decide whether emissions of an air pollutant from certain classes of aircraft engines cause or contribute to this air pollution. See Massachusetts v. EPA, 549 U.S. 497,533 (2007) (interpreting analogous provision in CAA section 202).
EPA is also issuing an Advance Notice of Proposed Rulemaking to provide an overview of and seek input on issues related to setting an international carbon dioxide standard for aircraft at the ICAO. ICAO is establishing global aircraft standards that achieve reductions in carbon dioxide emissions. EPA is proposing to promulgate findings for aircraft engine GHG emissions and use section 231 of the Clean Air Act to adopt and implement corresponding aircraft engine GHG emission standards here in the United States.
Comments to the proposed rulemaking and the proposed findings must be received by EPA on or before August 31, 2015.