40 CFR § 1065.1123 - General provisions for determining exhaust opacity.

---
identifier: "/us/cfr/t40/s1065.1123"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1065.1123 - General provisions for determining exhaust opacity."
title_number: 40
title_name: "Protection of Environment"
section_number: "1065.1123"
section_name: "General provisions for determining exhaust opacity."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "U"
subchapter_name: "AIR POLLUTION CONTROLS"
part_number: "1065"
part_name: "ENGINE-TESTING PROCEDURES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "70 FR 40516, July 13, 2005, unless otherwise noted."
cfr_part: "1065"
---


# 1065.1123 General provisions for determining exhaust opacity.

The provisions of § 1065.1125 describe system specifications for measuring percent opacity of exhaust for all types of engines. The provisions of § 1065.1127 describe how to use such a system to determine percent opacity of engine exhaust for applications other than locomotives. See 40 CFR 1033.525 for measurement procedures for locomotives.