Administrative Rules of Montana › Department 17 - ENVIRONMENTAL QUALITY › Chapter 17.8 - AIR QUALITY › Subchapter 17.8.8 - Prevention of Significant Deterioration of Air Quality › Rule 17.8.804 - AMBIENT AIR INCREMENTS

Current through Register Vol. 13, July 5, 2024
(1) 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
Particulate matter:
PM-2.5, annual arithmetic
							 mean.................................................................................
1
PM-2.5, 24-hr
							 maximum..............................................................................................
2
PM-10, annual arithmetic
							 mean..................................................................................
4
PM-10, 24-hr
							 maximum...............................................................................................
8
Sulfur dioxide
							 (SO2):
Annual arithmetic
							 mean...............................................................................................
2
24-hr
							 maximum.............................................................................................................
5
3-hr
							 maximum.............................................................................................................
25
Nitrogen dioxide
							 (NO2):
Annual arithmetic
							 mean...............................................................................................
2.5
CLASS II
Particulate matter:
PM-2.5, annual arithmetic
							 mean.................................................................................
4
PM-2.5, 24-hr
							 maximum..............................................................................................
9
PM-10, annual arithmetic
							 mean................................................................................
17
PM-10, 24-hr
							 maximum.............................................................................................
30
Sulfur dioxide
							 (SO2):
Annual arithmetic
							 mean.............................................................................................
20
24-hr
							 maximum...........................................................................................................
91
3-hr
							 maximum...........................................................................................................
512
Nitrogen dioxide
							 (NO2):
Annual arithmetic
							 mean.............................................................................................
25
CLASS III
Particulate matter:
PM-2.5, annual arithmetic
							 mean.................................................................................
8
PM-2.5, 24-hr
							 maximum............................................................................................
18
PM-10, annual arithmetic
							 mean................................................................................
34
PM-10, 24-hr
							 maximum.............................................................................................
60
Sulfur dioxide
							 (SO2):
Annual arithmetic
							 mean.............................................................................................
40
24-hr
							 maximum.........................................................................................................
182
3-hr
							 maximum............................................................................................................
700
Nitrogen dioxide
							 (NO2):
Annual arithmetic
							 mean..............................................................................................
50
(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.
75-2-111,
					 75-2-203, MCA; IMP,
					 75-2-202,
					 75-2-203,
					 75-2-204,
					 MCA;