GroundRules
40 CFR 51.151: Significant harm levels.
Where this section sits in the code
- Title 40—Protection of Environment
- CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY
- SUBCHAPTER C—AIR PROGRAMS
- PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS
- Subpart H—Prevention of Air Pollution Emergency Episodes
Each plan for a Priority I region must include a contingency plan which must, as a minimum, provide for taking action necessary to prevent ambient pollutant concentrations at any location in such region from reaching the following levels:
Sulfur dioxide—2.620 µg/m 3 (1.0 ppm) 24-hour average.
PM10—600 micrograms/cubic meter; 24-hour average.
Carbon monoxide—57.5 mg/m 3 (50 ppm) 8-hour average; 86.3 mg/m 3 (75 ppm) 4-hour average; 144 mg/m 3 (125 ppm) 1-hour average.
Ozone—1,200 ug/m 3 (0.6 ppm) 2-hour average.
Nitrogen dioxide—3.750 ug/m 3 (2.0 ppm) 1-hour average; 938 ug/m 3 (0.5 ppm) 24-hour average.
Collected 2026-08-27T02:26:04Z. Source file · JSON