40 CFR § 63.400 - Applicability.

---
identifier: "/us/cfr/t40/s63.400"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 63.400 - Applicability."
title_number: 40
title_name: "Protection of Environment"
section_number: "63.400"
section_name: "Applicability."
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: "2026-04-05"
last_updated: "2026-04-05"
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"
---


# 63.400 Applicability.

(a) The provisions of this subpart apply to all new and existing industrial process cooling towers that are operated with chromium-based water treatment chemicals and are either major sources or are integral parts of facilities that are major sources as defined in § 63.401.

(b) Table 1 of this subpart specifies the provisions of subpart A that apply and those that do not apply to owners and operators of IPCT's subject to this subpart.

[59 FR 46350, Sept. 8, 1994, as amended at 71 FR 17738, Apr. 7, 2006]