As EPA's most aggressive standards for heavy trucks to date, Phase 3 seeks to lower emissions by as much as 60% by 2045.
The Phase 3 standards will complement EPA's criteria pollutant standards for model year (MY) 2027 and beyond, which were finalized in December 2022.
EPA is proposing staggered time frames for cleaner heavy trucks to provide development time to refine technology for electric and fuel cell vehicles.
Depsite additional time needed to develop hydrogen infrastructure, EPA expects hydrogen-refueling needs can be met by MY 2030.
EPA requests comments and data on its proposed adoption rate, "including schedule and methods."
A public hearing is slated for May 2 or 3, with another possible on May 4, depending on the volume of responses received.