The United States Environmental Protection Agency (“EPA”) is submitting for publication in the Federal Register a proposed finding that lead air pollution may reasonably be anticipated to endanger the public health and welfare within the meaning of Section 231(a) of the Clean Air Act. See EPA-HQ-OAR-2022-0389.

EPA is also proposing a finding that engine emissions of lead from certain aircraft cause or contribute to lead air pollution that may reasonably be anticipated to endanger public health and welfare under Section 231(a) of the Clean Air Act.

The classes of aircraft engines and aircraft addressed by the proposal are denominated “covered aircraft engines” and as “covered aircraft.”

Covered aircraft engines in this context encompass an aircraft engine that is capable of using leaded aviation gasoline. Further, covered aircraft includes all aircraft and ultralight vehicles equipped with covered engines.

EPA states on behalf of the proposal that piston-engine aircraft are the largest single source of lead emissions to the air in the United States. Such aircraft are stated to contribute 70% of the lead entering the air annually. Further, emissions of lead from aircraft operating on leaded fuel are stated to cause elevated levels of lead in the air near airports.

The proposal sources from EPA’s previous scientific assessments for lead developed as part of its periodic reviews of the Air Quality Criteria (i.e., 108[a][2]) for lead and the lead Clean Air Act National Ambient Air Quality Standards. The agency states that such scientific assessments provide, in its view, a comprehensive review, synthesis, and evaluation of the most policy-relevant science building upon the conclusions of previous assessments.

The proposed action (i.e., consideration of the endangerment finding) is stated to be a:

. . . first step toward the application of EPA’s and the Federal Aviation Administration’s (“FAA”) statutory authorities to address lead pollution from aircraft.

EPA further states that if it makes a final determination that aircraft engine emissions of lead cause or contribute to lead air pollution that may reasonably be anticipated to endanger public health and welfare, it would propose regulatory standards for lead emissions from aircraft engines. This would also trigger the Federal Aviation Administration’s statutory mandate to prescribe standards for the composition or chemical or physical properties of an aircraft fuel or fuel additive to control or eliminate aircraft lead emissions.

A copy of the proposal can be downloaded here.