Wisconsin Administrative Code
Department of Natural Resources
NR 400-499 - Environmental Protection - Air Pollution Control
Chapter NR 404 - Ambient Air Quality
Section NR 404.05 - Ambient air increments

Universal Citation: WI Admin Code ยง NR 404.05

Current through August 26, 2024

(1) SCOPE. The ambient air increments apply to all attainment areas of the state.

(2) CLASS I INCREMENTS. In any area of this state classified under the Act as a class I area, the ambient air increments for PM 10, PM 2.5, sulfur dioxide, and nitrogen dioxide may not exceed the following amounts:

(a) PM10.
1. Annual arithmetic mean 4 micrograms per cubic meter

2. Twenty-four hour maximum 8 micrograms per cubic meter

(am) PM2.5.
1. Annual arithmetic mean 1 microgram per cubic meter

2. Twenty-four hour maximum 2 micrograms per cubic meter

(b) Sulfur dioxide.
1. Annual arithmetic mean 2 micrograms per cubic meter

2. Twenty-four hour maximum 5 micrograms per cubic meter

3. Three hour maximum 25 micrograms per cubic meter

(c) Nitrogen dioxide.
1. Annual arithmetic mean 2.5 micrograms per cubic meter

(3) CLASS II INCREMENTS. In any area of this state classified under the Act as a class II area, the ambient air increments for PM 10, PM 2.5, sulfur dioxide, and nitrogen dioxide may not exceed the following amounts:

(a) PM10.
1. Annual arithmetic mean 17 micrograms per cubic meter

2. Twenty-four hour maximum 30 micrograms per cubic meter

(am) PM2.5.
1. Annual arithmetic mean 4 micrograms per cubic meter

2. Twenty-four hour maximum 9 micrograms per cubic meter

(b) Sulfur dioxide.
1. Annual arithmetic mean 20 micrograms per cubic meter

2. Twenty-four maximum 91 micrograms per cubic meter

3. Three hour maximum 512 micrograms per cubic meter

(c) Nitrogen dioxide.
1. Annual arithmetic mean 25 micrograms per cubic meter

(4) CLASS III INCREMENTS. In any area of this state classified under the Act as a class III area, the ambient air increments for PM 10, PM 2.5, sulfur dioxide, and nitrogen dioxide may not exceed the following amounts:

(a) PM10.
1. Annual arithmetic mean 34 micrograms per cubic meter

2. Twenty-four hour maximum 60 micrograms per cubic meter

(am) PM2.5.
1. Annual arithmetic mean 8 micrograms per cubic meter

2. Twenty-four hour maximum 18 micrograms per cubic meter

(b) Sulfur dioxide.
1. Annual arithmetic mean 40 micrograms per cubic meter

2. Twenty-four hour maximum 182 micrograms per cubic meter

3. Three hour maximum 700 micrograms per cubic meter

(c) Nitrogen dioxide.
1. Annual arithmetic mean 50 micrograms per cubic meter

(5) EXCEPTION FOR NON-ANNUAL CONCENTRATIONS. Notwithstanding subs. (2) (intro.), (3) (intro.) and (4) (intro.), the ambient air increment of an air contaminant based on concentrations for any period other than an annual period may be exceeded during one such period per year.

(6) MAXIMUM CONCENTRATION. The maximum allowable concentration of any air contaminant in any attainment area may not exceed a concentration for such contaminant for each period of exposure equal to the maximum concentrations permitted under the primary or secondary air standards in s. NR 404.04.

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