USA - Revision of Tier 4 Criteria Pollutant Standards, Part 1: Amendments to Phase-In Schedule for Light-Duty and Medium-Duty Vehicles

​The U.S. Environmental Protection Agency (EPA) is proposing to reconsider part of its Tier 4 criteria pollutant standards for new light-duty and medium-duty motor vehicles, originally included in the final rule on Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles.