Criteria For Declaring Air Quality Episodes

An air quality episode will be declared by the Department when pollutant concentrations reach, or are forecasted to reach, and persist, at or above the levels listed below. Pollutant concentrations will be determined by the Department through its analysis of meteorological and ambient air quality monitoring data. (3-28-23) Pollutant Averaging Period Advisorya Alert Warning Emergencyb CO 8 hour NA 15 ppm 30 ppm 40 ppm NO2 1 hour NA 0.6 ppm 1.2 ppm 1.6 ppm 24 hour NA 0.15 ppm 0.3 ppm 0.4 ppm O3 1 hour NA 0.2 ppm 0.4 ppm 0.5 ppm SO2 24 hour NA 0.3 ppm 0.6 ppm 0.8 ppm PM2.5 1 hour 80 µg/m3 NA NA NA 24 hour 50 µg/m3 NA NA NA PM10 1 hour 385 µg/m3 NA NA NA 24 hour 150 µg/m3 350 µg/m3 420 µg/m3 500 µg/m3 Table Footnotes a. The Department may call an Advisory, if it determines, after evaluating the pertinent meteorology, weather conditions and air quality conditions such as visibility, and source parameters such as source type, strength, location and projected dura- tion, that an Advisory is required to protect the public health. b. The Department will only declare an emergency with specific concurrence of Governor. IDAHO ADMINISTRATIVE CODE IDAPA 58.01.01 Department of Environmental Quality Rules for the Control of Air Pollution in Idaho Section 557 Page 96