When the Director determines that conditions justify the proclamation of an air pollution episode stage, due to the accumulation of air contaminants in any place within the State, attaining levels which could, if sustained or exceeded, lead to a substantial threat to the health of persons, he shall be guided by the following criteria:

1. (a) Episode stages shall be determined and declared upon the basis of average concentrations recorded at any monitoring station in the State.
2. (b) If contamination and meteorology warrant, any advanced episode stage may be declared by the Director without first declaring a lesser degree of Alert or Watch. The Director shall, at his discretion, declare a lesser stage, the termination or the continuance of the advanced episode stage during such times when contamination and meteorological conditions moderate significantly after an advanced episode stage has been declared.

3. (c) Episode Watch. The Director shall declare an Episode Watch when one or more of the following events takes place:

   1. 1. An Atmospheric Stagnation Advisory is issued by the National Weather Service, stating that atmospheric conditions marked by a slow moving high pressure system, light winds, and temperature inversions are expected to affect the State of Alabama or portions thereof for the next thirty-six (36) hours.
   2. 2. A forecast by local meteorologist that stagnant atmospheric conditions as described above could result in high air pollution levels in Alabama or portions thereof.
   3. 3. Validated reports of abnormally high air pollution measurements, specifically, reaching or exceeding fifty percent (50%) of the Alert level of paragraph (4) of this Rule for at least three (3) consecutive hours at a given locality in the State.

4. (d) Alert. The Director shall declare an Alert when any one of the following contaminant concentrations is measured at any monitoring site and when adverse meteorological conditions can be expected to remain at these levels or higher for the next twelve (12) hours or more unless control measures are taken:

   1. 1. Sulfur Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.30 ppm (800 ug/m3) 

   2. 2. PM₁₀. Measured by a PM₁₀ sampler, 24 hour accumulation.

      24-hour average, 350 ug/m³

   3. 3. Carbon Monoxide. Measured by a continuous reference method analyzer or equivalent.

      8-hour average, 15 ppm (17 mg/m³)

   4. 4. Nitrogen Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.15 ppm (282 ug/m³)

      or 1-hour average, 0.6 ppm (1130 ug/m³)

   5. 5. Ozone. Measured by a continuous reference method analyzer or equivalent.

      1-hour average, 0.15 ppm (295 ug/m³)

5. (e) Warning. A Warning shall be declared by the Director when the concentrations of any of the following air contaminants measured at any monitoring site reach the following levels, and when adverse meteorological conditions can be expected to remain at these levels or higher for the next 12 hours or more unless control measures are taken:

   1. 1. Sulfur Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.6 ppm (1600 ug/m³)

   2. 2. PM₁₀ . Measured by a PM₁₀ sampler, 24-hour accumulation.

      24-hour average, 420 ug/m³

   3. 3. Carbon Monoxide. Measured by a continuous reference method analyzer or equivalent.

      8-hour average, 30 ppm (34 mg/m³)

   4. 4. Nitrogen Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.30 ppm (565 ug/m³) 

      1-hour average, 1.20 ppm (2260 ug/m³) 

   5. 5. Ozone. Measured by a continuous reference method analyzer or equivalent.

      1-hour average, 0.40 ppm (800 ug/m³)

6. (f) Emergency. An Emergency shall be declared by the Director when the following concentrations of air contaminants have been reached or when meteorological conditions can be expected to reach or exceed these levels at any monitoring site in the State for a period of twelve (12) hours or more unless control actions are taken:

   1. 1. Sulfur Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.8 ppm (2100 ug/m³) 

   2. 2. PM₁₀. Measured by a PM₁₀ sampler, 24-hour 1 0 accumulation.

      24-hour average, 500 ug/m³

   3. 3. Carbon monoxide. Measured by a continuous reference method analyzer or equivalent.

      8-hour average, 40 ppm (46 mg/m³)

   4. 4. Nitrogen Dioxide. Measured by a continuous reference method analyzer or equivalent.

      24-hour average, 0.40 ppm (750 ug/m³)

      1-hour average, 1.60 ppm (3000 ug/m³)

   5. 5. Ozone. Measured by a continuous reference method analyzer or equivalent.

      1-hour average, 0.50 ppm (1000 ug/m³)¹

7. (g) Termination.

   1. 1. The status reached by application of the Episode Criteria of this Rule shall remain in effect until the criteria for that level is no longer met. At such time, the next lower status will be assumed and such changes declared by the Director. Specifically:

      1. (i) When ambient contaminant concentrations fall below the critical levels for the stage, and a downward trend of concentrations is established; and
      2. (ii) When meteorological conditions that attended the high concentrations are no longer called for in official weather predictions.

   2. 2. A public declaration will take on one of the following forms:

      1. (i) Terminate "Emergency Status", resume "Warning Status" or "Alert Status", whichever is appropriate;
      2. (ii) Terminate "Warning Status", resume "Alert Status", or stage;
      3. (iii) Terminate "Episode Status".

      _______________________

      ¹(Revised March 30, 1976)

   3. 3. Upon termination of an "Episode Status", the Air Division will remain on internal "Episode Watch" until a return to normal operation is announced by the Director.
8. (h) Status Declaration Authority. The Director of the Alabama Department of Environmental Management, or his duly authorized agent, shall have the authority to make an announcement of internal Episode Watch and public declarations of Alert, Warning, and Emergency Status.

Author: James W. Cooper, John E. Daniel

Statutory Authority: Code of Ala. 1975, §§22-28-14, 22-22A-5, 22-22A-6, 22-22A-8.

History: Effective Date January 18, 1972. Amended: Filed October 17, 1996; effective November 21, 1996. Amended: Filed August 3, 2000; effective September 7, 2000.