Pollutant and Emissions Rate
Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Particulate matter: 25 tpy of particulate matter emissions
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy of sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless demonstrated not to be a PM2.5 precursor under paragraph (b)(50) of this section
Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2S): 10 tpy
Total reduced sulfur (including H2S): 10 tpy
Reduced sulfur compounds (including H2S): 10 tpy
Municipal waste combustor organics (measured as total tetra-through octa-chlorinated dibenzo-p-dioxins and dibenzofurans): 3.2 * 10-6 megagrams per year (3.5 * 10-6 tons per year)
Municipal waste combustor metals (measured as particulate matter): 14 megagrams per year (15 tons per year)
Municipal waste combustor acid gases (measured as sulfur dioxide and hydrogen chloride): 36 megagrams per year (40 tons per year)
Municipal solid waste landfills emissions (measured as nonmethane organic compounds): 45 megagrams per year (50 tons per year)
Pollutant | Maximum allowable increase (micrograms per cubic meter) |
Class I Area | |
PM2.5: | |
Annual arithmetic mean | 1 |
24-hr maximum | 2 |
PM10: | |
Annual arithmetic mean | 4 |
24-hr maximum | 8 |
Sulfur dioxide: | |
Annual arithmetic mean | 2 |
24-hr maximum | 5 |
3-hr maximum | 25 |
Nitrogen dioxide: | |
Annual arithmetic mean | 2.5 |
Class II Area | |
PM2.5: | |
Annual arithmetic mean | 4 |
24-hr maximum | 9 |
PM10: | |
Annual arithmetic mean | 17 |
24-hr maximum | 30 |
Sulfur dioxide: | |
Annual arithmetic mean | 20 |
24-hr maximum | 91 |
3-hr maximum | 512 |
Nitrogen dioxide: | |
Annual arithmetic mean | 25 |
Class III Area | |
PM2.5: | |
Annual arithmetic mean | 8 |
24-hr maximum | 18 |
PM10: | |
Annual arithmetic mean | 34 |
24-hr maximum | 60 |
Sulfur dioxide: | |
Annual arithmetic mean | 40 |
24-hr maximum | 182 |
3-hr maximum | 700 |
Nitrogen dioxide: | |
Annual arithmetic mean | 50 |
For any period other than an annual period, the applicable maximum allowable increase may be exceeded during one such period per year at any one location.
Note to paragraph (c)(50)(i)(f): No de minimis air quality level is provided for ozone. However, any net emissions increase of 100 tons per year or more of volatile organic compounds or nitrogen oxides subject to PSD would be required to perform an ambient impact analysis, including the gathering of ambient air quality data.
Pollutant | Maximum allowable increase (micrograms per cubic meter) |
PM2.5: | |
Annual arithmetic mean | 4 |
24-hr maximum | 9 |
PM10: | |
Annual arithmetic mean | 17 |
24-hr maximum | 30 |
Sulfur dioxide: | |
Annual arithmetic mean | 20 |
24-hr maximum | 91 |
3-hr maximum | 325 |
Nitrogen dioxide: | |
Annual arithmetic mean | 25 |
Maximum Allowable Increase
[Micrograms per cubic meter]
Period of exposure | Terrain areas | |
Low | High | |
24-hr maximum | 36 | 62 |
3-hr maximum | 130 | 221 |
40 C.F.R. §52.21
For FEDERAL REGISTER citations affecting § 52.21, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.
§ 52.21 has two paragraphs designated (i)(5)(i)(C).
Effective Date Note: At 76 FR 17556, Mar. 30, 2011, § 52.21(b)(2)(v) and (b)(3)(iii)(c) were stayed indefinitely. At 89 FR 84288, Oct. 22, 2024, stayed paragraph (b)(3)(iii)(c) was designated paragraph (b)(3)(iii)(C).