• Rule Summary
• Rule History
• Additional Resources

Rule Summary

The Environmental Protection Agency (EPA) is adopting a new combined emission standard for oxides of nitrogen (NO_x) and hydrocarbons (HC) for model year 2004 and later heavy-duty diesel engines used in trucks and buses. The new standard represents a 50 percent reduction in NO_x from the 1998 and later model year NO_x standard.

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• Final Rule: Control of Emissions of Air Pollution From Highway Heavy-Duty Engines (PDF)(37 pp, 432 K, published October 21, 1997)
• Final Regulatory Impact Analysis (PDF)(144 pp, 4 MB, EPA-420-R-97-011, September 1997)
• Summary and Analysis of Comments: Control of Emissions of Air Pollution from Highway Heavy-Duty Engines (PDF)(81 pp, 9 MB, September 1997, EPA-420-R-97-102 )

Rule History

• Proposed Rule and Related Materials

Additional Resources

Technical Support Document

• Estimated Economic Impact of New Emission Standards for Heavy-Duty On-Highway Engines (PDF)(87 pp, 422 K, EPA-420-R-97-009, March 1997)

Fact Sheet

• New Emission Standards For HeavyDuty Diesel Engines Used In Trucks And Buses (PDF)(4 pp, 14 K, EPA-420-F-97-016, October 1997)