Regulations for Smog, Soot, and Other Air Pollution from Commercial Trucks & Buses

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Overview

On February 12, 2026, EPA finalized its rescission of the 2009 Greenhouse Gas Endangerment Finding, which served as a prerequisite for regulating emissions from new motor vehicles and new motor vehicle engines. Absent this finding, EPA lacks statutory authority under Section 202(a) of the Clean Air Act to prescribe standards for GHG emissions. Therefore, EPA also finalized the repeal of all subsequent GHG emission standards from its regulations for light-, medium-, and heavy-duty on-highway vehicles and engines.

On July 9, 2026, EPA announced proposed regulatory amendments to certain compliance provisions and test procedures related to model years 2027 and later heavy-duty highway engines. These amendments would include changes to the regulatory useful life periods and the emission-related warranty periods. EPA also proposes to add clarity to certain regulatory compliance provisions and correct errors in the regulations to support the model year 2027 and later program for heavy-duty highway engines and vehicles.

List of Related Regulations

Below is a list of all regulations related to smog, soot, and other air pollution from commercial trucks and buses.

Click the regulation titles for additional information, including:
  • Rule summaries;
  • Regulatory impact analyses;
  • Comment summaries;
  • Rule histories; and
  • Fact sheets.*

*Note: Rule-related materials vary by rule.

Regulation TitleRegulation Date
(Year/Month)
Final Rule: Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles – Phase 32024/04
Final Rule: Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles2024/03
Proposed Rule: Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles2023/04
Final Rule and Related Materials for Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards2022/12
Final Rule: Improvements for Heavy-Duty Engine and Vehicle Test Procedures2021/06
Advance Notice of Proposed Rule: Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine Standards2020/01
Final Rule for Control of Air Pollution From New Motor Vehicles and New Motor Vehicle Engines; Non-Conformance Penalties for 2004 and later Model Year Emission Standards for Heavy-Duty Diesel Engines and Heavy-Duty Diesel Vehicles2002/08
Amendments Related to Tier 3 Motor Vehicle Emission and Fuel Standards, Nonroad Engine and Equipment Programs, and MARPOL Annex VI Implementation2015/05
Final Rule for Emergency Vehicle Rule—SCR Maintenance and Regulatory Flexibility for Nonroad Equipment2014/08
Direct Final Rule for Heavy-Duty Highway Program: Revisions for Emergency Vehicles2012/06
Direct Final Rule for In-Use Testing for Heavy-Duty Diesel Engines and Vehicles; Emission Measurement Accuracy Margins for Portable Emission Measurement Systems and Program Revisions2008/03
Final Rule for Control of Air Pollution From New Motor Vehicles and New Motor Vehicle Engines; Regulations Requiring Onboard Diagnostic Systems on 2010 and Later Heavy-Duty Engines Used in Highway Applications Over 14,000 Pounds2009/02
Final Rule for Control of Emissions of Air Pollution From New Motor Vehicles: In-Use Testing for Heavy-Duty Diesel Engines and Vehicles2005/06
Direct Final Rule for Amendments to Regulations for Heavy-Duty Diesel Engines2006/08
Final Rule for Control of Emissions of Air Pollution from 2004 and Later Model Year Heavy-Duty Highway Engines and Vehicles; Revision of Light-Duty On-Board Diagnostics Requirements2000/10
Final Rule for Control of Emissions of Air Pollution From Highway Heavy-Duty Engines1997/10
Direct Final Rule for Revisions to In-Use Testing for Heavy-Duty Diesel Engines and Vehicles; Emissions Measurement and Instrumentation; Not-to-Exceed Emission Standards; and Technical Amendments for Off-Highway Engines2010/11
Final Rule for Modification of Federal Onboard Diagnostic Regulations for: Light-Duty Vehicles, Light-Duty Trucks, Medium-Duty Passenger Vehicles, Complete Heavy-Duty Vehicles and Engines Intended for Use in Heavy-Duty Vehicles Weighing 14,000 Pounds GVWR2005/10
Direct Final Rule for Control of Air Pollution From New Motor Vehicles; Revisions to Motor Vehicle Diesel Fuel Sulfur Transition Provisions; and Technical Amendments to the Highway Diesel, Nonroad Diesel, and Tier 2 Gasoline Programs2005/11
Final Rule for Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards2014/04
Final Rule for Control of Air Pollution from New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements2001/01
Final Rule for Clean Alternative Fuel Vehicle and Engine Conversions2011/04
Final Rule for Emission Durability Procedures for New Light-Duty Vehicles, Light-Duty Trucks and Heavy-Duty Vehicles2006/01
Final Rule for Nonconformance Penalties for On-Highway Heavy-Duty Diesel Engines2012/09
Final Rule for Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles2011/09
Final Rule for Control of Air Pollution From New Motor Vehicles and New Motor Vehicle Engines: Evaporative and Refueling Emission Regulations for Gasoline and Methanol-Fueled Light-Duty Vehicles and Light-Duty Trucks and Heavy-Duty Vehicles; Technical Amen1995/08
Final Rule for on Ozone Transport Commission; Low Emission Vehicle Program for the Northeast Ozone Transport Region1995/01

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Last updated on July 10, 2026