Title 40: Protection of Environment
PART 51—REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS
Subpart H—Prevention of Air Pollution Emergency Episodes
Browse Previous | Browse Next
§ 51.151 Significant harm levels.
Each plan for a Priority I region must include a contingency plan which must, as a mimimum, 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]
