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US EPA proposes new emission standards for heavy-duty engines

7 March 2022

Today the US Environmental Protection Agency (EPA) proposed new, stronger emission standards for heavy-duty vehicles and engines starting in model year (MY) 2027. The proposed standards would reduce emissions of NOx and other pollutants from heavy-duty diesel and gasoline engines, and set updated ‘Phase 2’ GHG standards for certain categories of commercial vehicles.

The proposed emission standards are largely harmonized—beginning with MY 2027—with the California low NOx standards, so-called Omnibus regulation, adopted in August 2020. However, there are some differences in the emission limits and other provisions. The particulars can be found in the EPA proposed rule.

The EPA has proposed two regulatory options, both of which would set stronger emission standards for NOx beginning in MY 2027, adopt the LLC test cycle and emission standards in addition to the FTP & SET standards, increase regulatory useful life, and increase emissions-related warranty periods.

The above useful life periods are applicable to heavy heavy-duty engines; light- and medium-heavy-duty engines have shorter useful life periods. The proposed useful life periods are harmonized with those in the California Omnibus regulation.

The EPA proposal also introduces stronger standards for other pollutants: PM = 0.005 g/bhp-hr, HC = 0.040 g/bhp-hr, and CO = 6.0 g/bhp-hr.

The proposed revisions to existing Phase 2 GHG standards for MY2027 and later would set updated GHG emission standards for subsectors where electrification is advancing at a more rapid pace. These sectors include school buses, transit buses, commercial delivery trucks, and short-haul tractors.

The EPA intends to finalize the proposed emission standards by the end of 2022.

The proposal is the first step in EPA’s “Clean Trucks Plan”—a series of clean air and climate regulations that the agency intends to develop over the next three years. These planned future regulatory actions include:

Source: US EPA