The Environmental Protection Agency (EPA) is finalizing particulate matter (PM) emission standards and test procedures applicable to certain classes of engines used by civil subsonic jet airplanes (engines with rated output of greater than 26.7 kilonewtons (kN)) to replace the existing smoke standard for those engines. The EPA is adopting these standards under our authority in the Clean Air Act (CAA).

On January 5, 2021, the United States Court of Appeals for the Tenth Circuit granted the Environmental Protection Agency's (EPA) motion for a voluntary remand without vacatur of two parts of an EPA 2020 final rule approving Colorado's infrastructure state implementation plan (SIP) submission for the 2015 8-hour ozone national ambient air quality standards (NAAQS) (2020 final rule). In this document, EPA is taking final action to approve those two remanded parts of the 2020 final rule.

The Environmental Protection Agency (EPA) is approving revisions to the Utah Division of Administrative Rules (DAR) submitted by the State of Utah on May 21, 2020, May 28, 2020, November 3, 2020, and November 12, 2020. The EPA is taking this action pursuant to the Clean Air Act (CAA).

This final rule includes corrections, clarifications, additional flexibilities, and adjustment factors to improve the Greenhouse gas Emissions Model (GEM) compliance tool for heavy-duty vehicles while more closely matching the outputs produced by the original GEM version 3.0 that was used to establish the CO<INF>2</INF> standards for Model Years 2021 and later in the 2016 Heavy-duty Phase 2 final rule. Given the nature of this rule, there will be neither significant environmental impacts nor significant economic impacts.