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Electronic Code of Federal Regulations

e-CFR data is current as of December 5, 2019

Title 40Chapter ISubchapter CPart 51Subpart H → §51.151


Title 40: Protection of Environment
PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS
Subpart H—Prevention of Air Pollution Emergency Episodes


§51.151   Significant harm levels.

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/m3 (1.0 ppm) 24-hour average.

PM10—600 micrograms/cubic meter; 24-hour average.

Carbon monoxide—57.5 mg/m3 (50 ppm) 8-hour average; 86.3 mg/m3 (75 ppm) 4-hour average; 144 mg/m3 (125 ppm) 1-hour average.

Ozone—1,200 ug/m3 (0.6 ppm) 2-hour average.

Nitrogen dioxide—3.750 ug/m3 (2.0 ppm) 1-hour average; 938 ug/m3 (0.5 ppm) 24-hour average.

[51 FR 40668, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987]

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