December 16, 2022

Regulation of Lead Emissions from Aircraft Proposed

On October 17, 2022, EPA proposed a two-part action related to lead emissions under the CAA’s mobile source program. [87 FR 62753] First, the agency proposed to find lead air pollution may reasonably be anticipated to endanger public health and welfare according to CAA Section 231(a). Second, the agency proposed to find engine emissions of lead from aircraft burning leaded fuel (mostly piston-engine) cause or contribute to that lead air pollution. If finalized, the rule would not immediately create lead emission limits for affected aircraft engines. Instead, it would allow EPA and the FAA to do so at a later point in time. Comments may be submitted through January 17, 2023 via Docket ID No. EPA-HQ-OAR-2022-0389.

A 2019 survey from the FAA found there were more than 170,000 piston-engine aircraft in the United States. Most of these aircraft burn leaded aviation gasoline (avgas), accounting for the majority of lead emissions in the United States. The lead is added to avgas in the form of tetraethyl lead, but is typically emitted as other lead compounds that form particulate matter and are eventually deposited onto soils, groundwaters, and other surfaces. In 2017 alone, 470 tons of lead were emitted by aircraft using avgas, comprising 70% of the lead emitted into the air nationally that year. [87 FR 62778] In fact, many piston-engine aircraft engines cannot operate safely without the lead additive. Thus, despite the well-understood negative health effects (ranging from increased impulsivity to death) caused by lead exposure, regulation of leaded avgas has not been pursued until now.

Based upon the 2013 Integrated Science Assessment for Lead [78 FR 38318] and air quality criteria documents dating back to 1997, EPA believes the body of peer-reviewed evidence is sufficient for regulating lead emissions from avgas under CAA Section 231. This section of the CAA specifically addresses aviation fuels. If the agency finalizes these findings, it would be required to work with the FAA on developing an appropriate emission standard. The effective date of a standard must allow for the necessary time to develop and apply the requisite technology while considering the cost of compliance. An emission standard that would adversely affect safety or result in a significant noise increase is prohibited.

This determination is not the first of its kind for EPA. Most recently, the agency finalized a CAA Section 231 finding for greenhouse gases from aviation in 2016. [81 FR 54422]


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