StacksVerified U.S. regulatory reference

40 CFR Part 1033, Appendix A

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov

(a) Locomotives were originally subject to Tier 0, Tier 1, and Tier 2 emission standards described in paragraph (b) of this appendix as follows:

(1) The Tier 0 and Tier 1 standards in paragraph (b) of this appendix applied instead of the Tier 0 and Tier 1 standards of § 1033.101 for locomotives manufactured and remanufactured before January 1, 2010. For example, a locomotive that was originally manufactured in 2004 and remanufactured on April 10, 2011, was subject to the original Tier 1 standards specified in paragraph (b) of this appendix and became subject to the Tier 1 standards of § 1033.101 when it was remanufactured on April 10, 2011.

(2) The Tier 2 standards in paragraph (b) of this appendix applied instead of the Tier 2 standards of § 1033.101 for locomotives manufactured and remanufactured before January 1, 2013.

(b) The following NOX and PM standards applied before the dates specified in paragraph (a) of this appendix:

Type of standardYear of original manufactureTierStandards(g/bhp-hr)
NOXPM-primaryPM-alternate a
Line-haul1973-1992Tier 09.5 | 0.6 | 0.3
1993-2004Tier 17.4 | 0.45 | 0.22
2005-2011Tier 25.5 | 0.2 | 0.1
Switch1973-1992Tier 014 | 0.72 | 0.36
1993-2004Tier 111 | 0.54 | 0.27
2005-2011Tier 28.1 | 0.24 | 0.12

a Locomotives certified to the alternate PM standards are also subject to alternate CO standards of 10.0 for the line-haul cycle and 12.0 for the switch cycle.

(c) The original Tier 0, Tier 1, and Tier 2 standards for HC and CO emissions and smoke are the same standards identified in § 1033.101.

[88 FR 4486, Jan. 24, 2023]