15A NCAC 02D .0302      EPISODE CRITERIA

The Director may issue a proclamation of an air pollution alert, air pollution warning, or air pollution emergency if the Director determines that the accumulation of air contaminants in any place is attaining or has attained levels that could, if such levels are sustained or exceeded, lead to a threat to the health of the public. In deciding whether to issue such a proclamation, the Director shall be guided by the following criteria:

(1)           Alert. The alert level is that concentration of pollutants at which first stage control actions are to begin. The Secretary of the Department of Environmental Quality with the concurrence of the Governor shall proclaim an alert when any of the following levels is reached at any monitoring site and meteorological conditions are such that pollutant concentrations can be expected to remain at or exceed above levels for 12 or more hours or, in the case of ozone, the situation is likely to reoccur within the next 24-hours unless control actions are taken:

(a)           sulfur dioxide -- 800 µg/m³ (0.3 ppm), 24-hour average;

(b)           carbon monoxide -- 17 µg/m³ (15 ppm), eight-hour average;

(c)           ozone -- 400 µg/m³ (0.2 ppm), one-hour average;

(d)           nitrogen dioxide -- 1130 µg/m³ (0.6 ppm), one-hour average; 282 µg/m³ (0.15 ppm), 24-hour average; or

(e)           PM10--350 µg/m³ 24-hour average.

(2)           Warning. The warning level indicates that air quality is continuing to degrade and that additional abatement actions are necessary. The Secretary of the Department of Environmental Quality with the concurrence of the Governor shall proclaim a warning when any one of the following levels is reached at any monitoring site and meteorological conditions are such that pollutant concentrations can be expected to remain at or exceed above levels for 12 or more hours or, in the case of ozone, the situation is likely to reoccur within the next 24-hours unless control actions are taken:

(a)           sulfur dioxide -- 1600 µg/m³ (0.6 ppm),24-hour average

(b)           carbon monoxide -- 34 µg/m³ (30 ppm), eight-hour average;

(c)           ozone -- 800 µg/m³ (0.4 ppm), one-hour average;

(d)           nitrogen dioxide -- 2260 µg/m³ (1.2 ppm), one-hour average; 565 µg/m³ (0.3 ppm), 24-hour average; or

(e)           PM10 -- 420 µg/m³ 24-hour average.

(3)           Emergency. The emergency level indicates that air quality is continuing to degrade to a level that the most stringent control actions are necessary. The Secretary of the Department of Environmental Quality with the concurrence of the Governor shall declare an emergency when any one of the following levels is reached at any monitoring site and meteorological conditions are such that pollutant concentrations can be expected to remain at or exceed above levels for 12 or more hours or, in the case of ozone, the situation is likely to reoccur within the next 24-hours unless control actions are taken:

(a)           sulfur dioxide -- 2100 µg/m³ (0.8 ppm) 24-hour average;

(b)           carbon monoxide -- 46 µg/m³ (40 ppm), eight-hour average;

(c)           ozone -- 1000 µg/m³ (0.5 ppm), one-hour average;

(d)           nitrogen dioxide -- 3000 µg/m³ (1.6 ppm), one-hour average; 750 µg/m³ (0.4 p.p.m.), 24-hour average; or

(e)           PM10--500 µg/m³ 24-hour average.

(4)           Termination. After a proclamation has been issued, any level reached by application of these criteria shall remain in effect until the criteria for that level are no longer met. At that time the next lower level shall remain in effect until the criteria for that level are no longer met.

History Note:        Authority G.S. 143-215.3(a)(1); 143-215.3(a)(12);

Eff. February 1, 1976;

Amended Eff. July 1, 1998; July 1, 1988; July 1, 1984; June 1, 1980; December 1, 1976;

Readopted Eff. January 1, 2018.