ARM 17.8.804. AMBIENT AIR INCREMENTS

(1) In areas designated as Class I, II, or III, increases in pollutant concentration over the baseline concentration shall be limited to the following: (2) For any period other than an annual period, the applicable maximum allowable increase may be exceeded during one such period per year at any one location. Pollutant Maximum allowable increase (micrograms per cubic meter) CLASS I Particulate matter: PM-10, annual arithmetic mean ......................................4 PM-10, 24-hr maximum ...................................................8 Sulfur dioxide: Annual arithmetic mean ...................................................2 24-hr maximum .................................................................5 3-hr maximum .................................................................25 Nitrogen dioxide: Annual arithmetic mean ...................................................2.5 CLASS II Particulate matter: PM-10, annual arithmetic mean ....................................17 PM-10, 24-hr maximum .................................................30 Sulfur dioxide: Annual arithmetic mean .................................................20 24-hr maximum ...............................................................91 3-hr maximum ...............................................................512 Nitrogen dioxide: Annual arithmetic mean .................................................25 CLASS III Particulate matter: PM-10, annual arithmetic mean ....................................34 PM-10, 24-hr maximum .................................................60 Sulfur dioxide: Annual arithmetic mean .................................................40 24-hr maximum .............................................................182 3-hr maximum ................................................................700 Nitrogen dioxide: Annual arithmetic mean ................................................. 50