40 CFR § 63.6580 - What is the purpose of subpart ZZZZ?

---
identifier: "/us/cfr/t40/s63.6580"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 63.6580 - What is the purpose of subpart ZZZZ?"
title_number: 40
title_name: "Protection of Environment"
section_number: "63.6580"
section_name: "What is the purpose of subpart ZZZZ?"
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "63"
part_name: "NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES"
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"
regulatory_source: "57 FR 61992, Dec. 29, 1992, unless otherwise noted."
cfr_part: "63"
---


# 63.6580 What is the purpose of subpart ZZZZ?

Subpart ZZZZ establishes national emission limitations and operating limitations for hazardous air pollutants (HAP) emitted from stationary reciprocating internal combustion engines (RICE) located at major and area sources of HAP emissions. This subpart also establishes requirements to demonstrate initial and continuous compliance with the emission limitations and operating limitations.

[73 FR 3603, Jan. 18, 2008]