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e-CFR data is current as of September 17, 2020

Title 40Chapter ISubchapter CPart 51 → Subpart H

Title 40: Protection of Environment

Subpart H—Prevention of Air Pollution Emergency Episodes

§51.150   Classification of regions for episode plans.
§51.151   Significant harm levels.
§51.152   Contingency plans.
§51.153   Reevaluation of episode plans.

Source: 51 FR 40668, Nov. 7, 1986, unless otherwise noted.

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§51.150   Classification of regions for episode plans.

(a) This section continues the classification system for episode plans. Each region is classified separately with respect to each of the following pollutants: Sulfur oxides, particulate matter, carbon monoxide, nitrogen dioxide, and ozone.

(b) Priority I Regions means any area with greater ambient concentrations than the following:

(1) Sulfur dioxide—100 µg/m3 (0.04 ppm) annual arithmetic mean; 455 µg/m3 (0.17 ppm) 24-hour maximum.

(2) Particulate matter—95 µg/m3 annual geometric mean; 325 µg/m3 24-hour maximum.

(3) Carbon monoxide—55 mg/m3 (48 ppm) 1-hour maximum; 14 mg/m3 (12 ppm) 8-hour maximum.

(4) Nitrogen dioxide—100 µg/m3 (0.06 ppm) annual arithmetic mean.

(5) Ozone—195 µg/m3 (0.10 ppm) 1-hour maximum.

(c) Priority IA Region means any area which is Priority I primarily because of emissions from a single point source.

(d) Priority II Region means any area which is not a Priority I region and has ambient concentrations between the following:

(1) Sulfur Dioxides—60-100 µg/m3 (0.02-0.04 ppm) annual arithmetic mean; 260-445 µg/m3 (0.10-0.17 ppm) 24-hour maximum; any concentration above 1,300 µg/m3 (0.50 ppm) three-hour average.

(2) Particulate matter—60-95 µg/m3 annual geometric mean; 150-325 µg/m3 24-hour maximum.

(e) In the absence of adequate monitoring data, appropriate models must be used to classify an area under paragraph (b) of this section, consistent with the requirements contained in §51.112(a).

(f) Areas which do not meet the above criteria are classified Priority III.

[51 FR 40668, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993]

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§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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§51.152   Contingency plans.

(a) Each contingency plan must—

(1) Specify two or more stages of episode criteria such as those set forth in appendix L to this part, or their equivalent;

(2) Provide for public announcement whenever any episode stage has been determined to exist; and

(3) Specify adequate emission control actions to be taken at each episode stage. (Examples of emission control actions are set forth in appendix L.)

(b) Each contingency plan for a Priority I region must provide for the following:

(1) Prompt acquisition of forecasts of atmospheric stagnation conditions and of updates of such forecasts as frequently as they are issued by the National Weather Service.

(2) Inspection of sources to ascertain compliance with applicable emission control action requirements.

(3) Communications procedures for transmitting status reports and orders as to emission control actions to be taken during an episode stage, including procedures for contact with public officials, major emission sources, public health, safety, and emergency agencies and news media.

(c) Each plan for a Priority IA and II region must include a contingency plan that meets, as a minimum, the requirements of paragraphs (b)(1) and (b)(2) of this section. Areas classified Priority III do not need to develop episode plans.

(d) Notwithstanding the requirements of paragraphs (b) and (c) of this section, the Administrator may, at his discretion—

(1) Exempt from the requirements of this section those portions of Priority I, IA, or II regions which have been designated as attainment or unclassifiable for national primary and secondary standards under section 107 of the Act; or

(2) Limit the requirements pertaining to emission control actions in Priority I regions to—

(i) Urbanized areas as identified in the most recent United States Census, and

(ii) Major emitting facilities, as defined by section 169(1) of the Act, outside the urbanized areas.

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§51.153   Reevaluation of episode plans.

(a) States should periodically reevaluate priority classifications of all Regions or portion of Regions within their borders. The reevaluation must consider the three most recent years of air quality data. If the evaluation indicates a change to a higher priority classification, appropriate changes in the episode plan must be made as expeditiously as practicable.

(b) [Reserved]

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