---
kind: "section"
citation: "40 C.F.R. § 87.21"
title: "40"
number: "87.21"
heading: "Exhaust emission standards for Tier 4 and earlier engines."
url: "https://uscodex.org/cfr/40/87.21"
---

# §87.21. Exhaust emission standards for Tier 4 and earlier engines.


Exhaust emission standards apply to new aircraft engines as described in [40 CFR 1031.40 through 1031.90](/cfr/40/1031.40..1031.90.md).


## Notes

### Authority

Authority: 42 U.S.C. 7401 et seq.

### Source

Source: 87 FR 72350, Nov. 23, 2022, unless otherwise noted.