Title 42 › Chapter CHAPTER 85— - AIR POLLUTION PREVENTION AND CONTROL › Subchapter SUBCHAPTER I— - PROGRAMS AND ACTIVITIES › Part Part C— - Prevention of Significant Deterioration of Air Quality › Subpart subpart i— - clean air › § 7479
Defines key words used here and what kinds of sources and actions are covered. It explains what counts as a major emitting facility, when construction is considered to have started, what best available control technology means, and how to set the baseline pollution level. A "major emitting facility" is a list of large industrial sources (for example, big power plants and boilers over 250 million British thermal units per hour, refineries, cement plants, metal smelters, municipal incinerators that take more than 50 tons of refuse per day, petroleum storage over 300,000 barrels, and similar plants) that emit or could emit 100 tons per year or more of any pollutant, and it also covers any other source with the potential to emit 250 tons per year or more; new or modified nonprofit health or education facilities are excluded if the State has exempted them. "Commenced" means the owner has all required preconstruction permits and has either begun continuous on-site construction or signed binding contracts that force construction to proceed. "Necessary preconstruction approvals or permits" are the permits the permitting authority requires before starting work. "Construction" also includes modifying an existing source. "Best available control technology" is a case-by-case emission limit requiring the maximum pollution reduction achievable for each regulated pollutant, set after considering energy, environmental, and economic effects; it can include cleaner fuels or treatment methods, must not let emissions exceed any applicable air-quality standards, and cannot allow emissions to rise above levels that would have been required before November 15, 1990 when using clean fuels. "Baseline concentration" is the ambient pollution level when the first permit application is filed in an area, based on EPA or State data and required monitoring; it must count emissions from major sources whose construction began before January 6, 1975 but were not yet operating, while sulfur oxides and particulate emissions from sources that began construction after January 6, 1975 are excluded from the baseline and instead counted against allowed increases.
Full Legal Text
The Public Health and Welfare — Source: USLM XML via OLRC
Legislative History
Reference
Citation
42 U.S.C. § 7479
Title 42 — The Public Health and Welfare
Last Updated
Apr 6, 2026
Release point: 119-73