EPA Takes First Steps to Address GHG
Emissions from Aircraft Engines
The EPA Administrator is proposing to find that greenhouse gas
(GHG) emissions from certain classes of engines used in aircraft
contribute to the air pollution that causes climate change and endangers
public health and welfare under section 231 (a) of the Clean Air Act
(CAA or the Act). The EPA is not at this time proposing aircraft
engine GHG emission standards.
The EPA is also issuing an Advance Notice of Proposed Rulemaking
that provides information on the process for setting an international
CO2 emissions standard for aircraft at the International Civil Aviation
Organization (ICAO), and describes and seeks input on the potential
use of section 231 of the Clean Air Act to adopt and implement the
corresponding international aircraft engine CO2 emissions standard
domestically.
The Clean Air Act and Aircraft Regulation
The EPA has been engaged in reducing harmful air pollution from aircraft engines
since 1973. Section 231 of the Clean Air Act directs the EPA to issue standards
addressing aircraft engine pollutant emissions, if in the Administrator's judgment
they cause or contribute to air pollution which may reasonably be anticipated to
endanger public health or welfare. Under the Clean Air Act, the EPA consults with
the Federal Aviation Administration as we develop aircraft engine emission stan-
dards, ensuring that any standards set do not adversely affect safety or increase noise.
Section 232 of the Clean Air Act then requires that the FAA ensure compliance
with the emissions standards set by the EPA.
The EPA and the FAA have traditionally worked within the International Civil
Aviation Organization (ICAO), a specialized body of the United Nations focused on
aviation and comprised of 191 member states, to first establish international emission
standards. Subsequently, the EPA has initiated rulemakings under Clean Air Act
section 231 to establish domestic standards equivalent to ICAO's standards. Aircraft
&EPA
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-15-023
June 2015
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engine standards for other exhaust pollutants including hydrocarbons, oxides of nitrogen, carbon
monoxide, and smoke already exist and were developed in accordance with this international
process. The proposed GHG cause and contribution findings for aircraft engines are an initial
step toward potentially aligning future international and U.S. standards for CO2 emissions from
aircraft engines.
Background
In 2009 the EPA issued findings under Clean Air Act section 202 that GHG emissions from
motor vehicles cause or contribute to the air pollution that causes climate change endangering
public health and welfare. Subsequent to this finding, EPA adopted GHG emission standards for
motor vehicles under section 202 of the Act. We are not reopening or revising our prior finding
under CAA section 202(a) in this proposed action.
To address GHG emissions from aircraft, EPA would first issue a separate and final finding under
section 231 of the Act concluding that GHGs from aircraft engines contribute to the pollution
that causes climate change thus endangering public health and welfare. In this proposed action,
the EPA relies upon the extensive scientific and technical evidence in the record supporting the
2009 finding, and builds on it with more recent major scientific assessments. Since 2009, the
science on climate change has strengthened lending further support to the judgment that GHGs
in the atmosphere endanger public health and welfare for purposes of section 231.
The Administrator's proposed findings come in response to a citizen petition submitted by
Friends of the Earth, Oceana, the Center for Biological Diversity, and Earthjustice (Petitioners)
requesting that the EPA issue a GHG endangerment finding and standards under section 231 (a)
(2) (A) of the Act for GHG emissions from aircraft engines. Further, the EPA anticipates that
ICAO will adopt a final international aircraft CO2 emissions standard in February 2016. This
proposal and any final GHG endangerment and cause or contribute findings for aircraft engines
are part of preparing for a possible subsequent domestic rulemaking process to adopt the corre-
sponding international aircraft CO2 emissions standard under CAA section 231.
Aircraft GHG Emissions
The U.S. transportation sector is a significant contributor to total U.S. and global anthropogen-
ic GHG emissions. Aircraft remain the single largest GHG-emitting transportation source not
yet subject to GHG standards in the U.S.
U.S. aircraft emit:
• 11 percent of GHG emissions from the transportation sector in the U.S.
• 3 percent of total U.S. GHG emissions.
• 29 percent of GHG emissions from all aircraft globally.
• 0.5 percent of total global GHG emissions.
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Proposed Endangerment and Cause and Contribute Findings
The EPA Administrator is proposing to find that GHG emissions from certain classes of engines
used primarily in commercial aircraft contribute to the air pollution that causes climate change
and endangers public health and welfare. Specifically, she proposes to find that GHG concentra-
tions in the atmosphere endanger the public health and welfare of current and future genera-
tions within the meaning of section 231 (a) of the Clean Air Act. She proposes to make this
finding specifically with respect to the same six well-mixed GHGs -- carbon dioxide, methane,
nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride - that together
were defined as the relevant air pollution in the 2009 Endangerment Finding under section
202(a) of the Clean Air Act. The Administrator is also proposing to find that GHG pollutant
emissions from certain classes of engines used in aircraft are contributing to this mix of GHGs in
the atmosphere.
Proposed Scope of Covered Aircraft Engines
The Administrator proposes to find that GHG emissions from engines used in U.S. subsonic jet
aircraft with a maximum takeoff mass (MTOM) greater than 5,700 kilograms and in subsonic
propeller driven (e.g., turboprop) aircraft with a MTOM greater than 8,618 kilograms, contrib-
ute to the GHG air pollution that endangers public health and welfare. Examples of covered
aircraft would include smaller jet aircraft such as the Cessna Citation CJ2+ and the Embraer
El70, up to and including the largest 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 Administrator is not at this time proposing a contribution finding for GHG emissions from
engines used in military aircraft or smaller aircraft such as smaller turboprops, smaller jet aircraft,
piston-engine aircraft, and helicopters.
Advance Notice of Proposed Rulemaking (ANPR)
Over the past five years, the International Civil Aviation Organization (ICAO), a specialized
body of the United Nations with 191 member states, has been working with the aviation indus-
try and environmental groups to develop a coordinated, international CO2 emissions standard
for aircraft. EPA and the Federal Aviation Administration (FAA) represent the United States
on ICAO's Committee on Aviation Environmental Protection (CAEP), and are working to
ensure that CAEP develops an international standard that achieves meaningful CO2 emissions
reductions through policies that are equitable across national boundaries. This international
standard is expected to be adopted in early 2016.
Today's notice is an initial step in the process for EPA to adopt CO2 standards promulgated by
ICAO in the future. It provides the public and stakeholders with information on the ICAO
standard-setting process and requests input on the setting of these standards. The EPA is seeking
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comments from all interested parties, including small businesses, on a variety of issues related to
setting CO2 standards for aircraft, including:
• The appropriate effective dates for the potential international CO2 standard
• The appropriate stringency levels for the CO2 standard
• Whether international standards should apply to new in-production aircraft as well as
new aircraft types
Participation
We welcome your comments on these proposed endangerment and contribution findings and
ANPR. Comments will be accepted for 60 days beginning when this proposal is published
in the Federal Register. All comments should be identified by Docket ID No. EPA-HQ-
OAR-2014-0828 and submitted by one of the following methods:
Internet: www.regulations.gov
E-mail: A-and'R'Docket@epa.gov
Mail:
Environmental Protection Agency
Air and Radiation Docket and Information Center (6102T)
1200 Pennsylvania Avenue NW
Washington, DC 20460
Hand Delivery:
EPA West building
EPA Docket Center (Room 3340)
1301 Constitution Avenue NW
Washington, DC
You should consult the Federal Register notice for this proposal for more information about
how to submit comments, when the comment period will close, and about where and if a public
hearing will be held.
For More Information
You can access the proposal and ANPR on EPA's Office of Transportation and Air Quality
(OTAQ) Website:
www.epa.gov/otaq/aviation.htm
For more information on this proposal and ANPR, please contact the U.S. Environmental
Protection Agency, Office of Transportation and Air Quality at:
E-mail: otaq@epa.gov
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