US lawFederal (United States)RegulationsTitle 40 CFR — Protection of EnvironmentChapter I — ENVIRONMENTAL PROTECTION AGENCYPart 63 — NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIESSubpart Q — National Emission Standards for Hazardous Air Pollutants for Industrial Process Cooling Towers63.40240 C.F.R. § 63.402Standard.Last amended: 2016Year: 2026Length: 17 wordsOfficial source Cite as 40 C.F.R. § 63.402 (2026)No owner or operator of an IPCT shall use chromium-based water treatment chemicals in any affected IPCT.Previous40 C.F.R. § 63.401Next40 C.F.R. § 63.403