The EPA is analyzing air quality modeling and monitoring information to make a determination, under section 231 of the Clean Air Act, as to whether lead emissions from aircraft engines operating on leaded fuel cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare. In this action, EPA would issue a Notice of Proposed Rulemaking that describes the proposed determination regarding lead emissions from general aviation aircraft. This would include a description of analyses that EPA conducted to inform the proposed determination, such as the lead emissions inventory relevant to use of leaded aviation gasoline, air quality monitoring, air quality modeling, and potential exposure information.