Abstract:

As California finalizes an omnibus rule that will require a 90% reduction in nitrogen oxide (NOx) emissions from heavy-duty vehicles in the 2024–2027 timeframe, other states, including New York, New Jersey, and Massachusetts, have indicated that they will also adopt California’s rule. Meanwhile, the United States Environmental Protection Agency (EPA) has been directed by the White House to propose by January 2022 a stringent national standard for NOx emissions from heavy-duty vehicles (HDVs) that will apply nationwide starting around 2027. These proposals and plans continue a series of emissions regulations in the United States lowering NOx emissions limits from heavy-duty vehicles that began in 1985. These standards have been, and the new ones will be, technology neutral, meaning that they do not specify what technologies, including powertrains, manufacturers must use to comply but only that they must comply.