Ambient Air Increments

Section 204.900  Ambient Air Increments a)         In areas designated as Class I, II or III, increases in pollutant concentration over the baseline concentration shall be limited to the following: Pollutant Maximum allowable increase (micrograms per cubic meter) Class I Area PM 2.5 : Annual arithmetic mean 1 24-hr maximum 2 PM 10 : Annual arithmetic mean 4 24-hr maximum 8 SO 2 : Annual arithmetic mean 2 24-hr maximum 5 3-hr maximum 25 NO 2 : Annual arithmetic mean 2.5 Class II Area PM 2.5 : Annual arithmetic mean 4 24-hr maximum 9 PM 10 : Annual arithmetic mean 17 24-hr maximum 30 SO 2 : Annual arithmetic mean 20 24-hr maximum 91 3-hr maximum 512 NO 2 : Annual arithmetic mean 25 Class III Area PM 2.5 : Annual arithmetic mean 8 24-hr maximum 18 PM 10 : Annual arithmetic mean 34 24-hr maximum 60 SO 2 : Annual arithmetic mean 40 24-hr maximum 182 3-hr maximum 700 NO 2 : Annual arithmetic mean 50 b)         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.