Regulatory Alert: EPA Releases Proposed Endangerment Finding for Piston-Engine Aircraft Lead Emissions
October 7, 2022
The U.S. Environmental Protection Agency (EPA) released a proposed endangerment finding on October 7 that lead emissions from piston-engine aircraft cause or contribute to air pollution that may reasonably be anticipated to endanger public health and welfare. The proposed finding is the first step in a long process that, if finalized, would require the Federal Aviation Administration (FAA) to enforce aircraft engine lead emission standards through the aircraft certification process.
In terms of what this means for airports, there are no immediate impacts. Despite EPA's proposed actions, aircraft operators may continue to use leaded avgas, and airports and FBOs are not precluded from selling the fuel. However, AAAE, FAA, and our industry partners recognize the need to transition to an unleaded avgas and are working together through the Eliminate Aviation Gasoline Lead Emissions (EAGLE) Initiative to ensure an accelerated and smooth transition.
Background. Under the Clean Air Act, EPA has the authority to promulgate emission standards for specific air pollutants that are derived from aircraft engines, such as lead emissions from piston-engine aircraft that use leaded avgas. However, before developing these standards, the agency must determine that (a) the lead air pollution under consideration may reasonably be anticipated to endanger public health or welfare, and (b) emission of the lead air pollutant from piston-engine aircraft cause or contribute to this air pollution. 
Proposed Endangerment Finding. The purpose of the proposal released today is to outline the agency's proposed finding that lead emissions from engines that use leaded avgas cause or contribute to air pollution that may reasonably be anticipated to endanger public health and welfare. As support for its proposed finding, EPA cites a wide range of scientific information regarding the effects that lead emissions can have on the health of humans, particularly children, and on agriculture products and aquatic ecosystems. The agency noted that piston-engine aircraft are the largest single source of lead emissions to the air, contributing 70% of the lead entering the air annually. EPA has also found “elevated levels of lead in air near airports.“
EAGLE Initiative. This year, AAAE has significantly increased its focus on the challenges that the airport community, especially GA airports, have been facing regarding lead emissions generated by piston-engine aircraft and leaded avgas. AAAE continues to actively participate as a member of a public-private partnership called the EAGLE Initiative, which is aimed at accelerating the transition to unleaded avgas for piston-engine aircraft by 2030. The initiative includes FAA, the American Petroleum Institute, and the major GA trade associations.
Progress on Unleaded Avgas Alternatives. As outlined in our September 1 Regulatory Alert, the industry witnessed a major development when FAA approved supplemental type certificates (STCs) to allow the General Aviation Modifications, Inc.'s (GAMI) 100-octane unleaded fuel (G100UL) to be used in all piston-engine GA airplanes with FAA type certificates. While this is certainly a positive development, we continue to work with our industry partners and airport members to understand how production of G100UL can be scaled up and what types of infrastructure improvements will be needed to support more widespread use of this and other fuels. 
What's Next? After EPA publishes the proposed endangerment finding in the Federal Register, industry stakeholders and the public will have 90 days to submit comments to the agency. The deadline is expected to be in January 2023. The proposed finding is the first step in a long process that, if finalized, would require FAA to enforce aircraft engine lead emission standards through the aircraft certification process. Below is an anticipated timeline for EPA and FAA to regulate aircraft lead emissions.
• Oct.“Nov. 2022: EPA indicated that the agency would host a virtual public hearing on the proposed finding in the near term. The purpose will be to solicit feedback from the public. 
• Jan. 2023: Once published in the Federal Register, the public and industry stakeholders will have 90 days to respond to the proposed finding. This deadline is expected to be in January 2023. 
• Fall 2023: EPA is expected to issue a final endangerment finding after evaluating comments on the proposal. 
• 2023“2025: EPA is expected to propose regulatory standards for lead emissions from aircraft engines. 
• 2025“2027: FAA is expected to promulgate certification standards that would require engine manufacturers to comply with the lead emission standards developed by EPA. 
• 2030: FAA and industry, through the EAGLE Initiative, have set 2030 as the goal for fully transitioning to unleaded avgas. 
Additional Resources
• EPA's Proposed Endangerment Finding for Piston-Engine Aircraft Lead Emissions 
• EPA's Fact Sheet on the Proposed Finding 
• EPA's Technical Support Document (TSD) for the Proposed Finding 
• EPA's Press Release on the Proposed Finding 
• FAA-Industry EAGLE Initiative Briefing 
The U.S. Environmental Protection Agency (EPA) released a proposed endangerment finding on October 7 that lead emissions from piston-engine aircraft cause or contribute to air pollution that may reasonably be anticipated to endanger public health and welfare. The proposed finding is the first step in a long process that, if finalized, would require the Federal Aviation Administration (FAA) to enforce aircraft engine lead emission standards through the aircraft certification process.
In terms of what this means for airports, there are no immediate impacts. Despite EPA's proposed actions, aircraft operators may continue to use leaded avgas, and airports and FBOs are not precluded from selling the fuel. However, AAAE, FAA, and our industry partners recognize the need to transition to an unleaded avgas and are working together through the Eliminate Aviation Gasoline Lead Emissions (EAGLE) Initiative to ensure an accelerated and smooth transition.
Background. Under the Clean Air Act, EPA has the authority to promulgate emission standards for specific air pollutants that are derived from aircraft engines, such as lead emissions from piston-engine aircraft that use leaded avgas. However, before developing these standards, the agency must determine that (a) the lead air pollution under consideration may reasonably be anticipated to endanger public health or welfare, and (b) emission of the lead air pollutant from piston-engine aircraft cause or contribute to this air pollution. 
Proposed Endangerment Finding. The purpose of the proposal released today is to outline the agency's proposed finding that lead emissions from engines that use leaded avgas cause or contribute to air pollution that may reasonably be anticipated to endanger public health and welfare. As support for its proposed finding, EPA cites a wide range of scientific information regarding the effects that lead emissions can have on the health of humans, particularly children, and on agriculture products and aquatic ecosystems. The agency noted that piston-engine aircraft are the largest single source of lead emissions to the air, contributing 70% of the lead entering the air annually. EPA has also found “elevated levels of lead in air near airports.“
EAGLE Initiative. This year, AAAE has significantly increased its focus on the challenges that the airport community, especially GA airports, have been facing regarding lead emissions generated by piston-engine aircraft and leaded avgas. AAAE continues to actively participate as a member of a public-private partnership called the EAGLE Initiative, which is aimed at accelerating the transition to unleaded avgas for piston-engine aircraft by 2030. The initiative includes FAA, the American Petroleum Institute, and the major GA trade associations.
Progress on Unleaded Avgas Alternatives. As outlined in our September 1 Regulatory Alert, the industry witnessed a major development when FAA approved supplemental type certificates (STCs) to allow the General Aviation Modifications, Inc.'s (GAMI) 100-octane unleaded fuel (G100UL) to be used in all piston-engine GA airplanes with FAA type certificates. While this is certainly a positive development, we continue to work with our industry partners and airport members to understand how production of G100UL can be scaled up and what types of infrastructure improvements will be needed to support more widespread use of this and other fuels. 
What's Next? After EPA publishes the proposed endangerment finding in the Federal Register, industry stakeholders and the public will have 90 days to submit comments to the agency. The deadline is expected to be in January 2023. The proposed finding is the first step in a long process that, if finalized, would require FAA to enforce aircraft engine lead emission standards through the aircraft certification process. Below is an anticipated timeline for EPA and FAA to regulate aircraft lead emissions.
• Oct.“Nov. 2022: EPA indicated that the agency would host a virtual public hearing on the proposed finding in the near term. The purpose will be to solicit feedback from the public. 
• Jan. 2023: Once published in the Federal Register, the public and industry stakeholders will have 90 days to respond to the proposed finding. This deadline is expected to be in January 2023. 
• Fall 2023: EPA is expected to issue a final endangerment finding after evaluating comments on the proposal. 
• 2023“2025: EPA is expected to propose regulatory standards for lead emissions from aircraft engines. 
• 2025“2027: FAA is expected to promulgate certification standards that would require engine manufacturers to comply with the lead emission standards developed by EPA. 
• 2030: FAA and industry, through the EAGLE Initiative, have set 2030 as the goal for fully transitioning to unleaded avgas. 
Additional Resources
• EPA's Proposed Endangerment Finding for Piston-Engine Aircraft Lead Emissions 
• EPA's Fact Sheet on the Proposed Finding 
• EPA's Technical Support Document (TSD) for the Proposed Finding 
• EPA's Press Release on the Proposed Finding 
• FAA-Industry EAGLE Initiative Briefing 
