NR 404.05 Ambient air increments. NR 404.06 Measurement of ambient air quality. NR 404.07 Interpretation of air quality data with respect to air standards. NR 404.08 Guidelines for application of air standards. Ch. NR 404 NoteNote: Chapter NR 155 as it existed on March 31, 1972 was repealed and a new chapter NR 155 was created, Register, March, 1972, No. 195, effective April 1, 1972. Chapter NR 155 was renumbered chapter NR 404, Register, July, 1985. Ch. NR 404 NoteNote: Air standards are definitions of the characteristics of ambient air quality which, in terms of present day knowledge, need to be maintained in order to protect the public health and welfare and our environment from adverse effects of air pollution.
Ch. NR 404 NoteThe purpose of air standards should be viewed as goals or objectives to be achieved by these and other rules of the department, by regional implementation plans, and by enforcement programs of both state and local governments as population, industrial activity and land use changes.
Ch. NR 404 NoteThe standards are meaningful for pollution control when applied to achieve and maintain desired air quality as expressed by the standards.
Ch. NR 404 NoteBecause of variation in population, transportation, and industrial densities, in addition to variation in terrain and meteorology, equal air quality may not be achieved throughout a region or area.
Ch. NR 404 NoteThese standards conform to national ambient air quality standards. They are subject to review as knowledge of the effects of air pollution on health, plant and animal life, property, visibility, and our environment increases.
Ch. NR 404 NoteThese standards are promulgated pursuant to ch. 285, Stats., which directs the department of natural resources to undertake a comprehensive program to manage and protect the state’s air resources. These rules are one part of that program. NR 404.01(1)(1) Applicability. The air standards of this chapter apply to the entire state without exception. The ambient air increments of this chapter apply to all attainment areas of the state. NR 404.01(2)(2) Purpose. This chapter is adopted under ss. 285.11, 285.13 and 285.21, Stats., to establish geographic air regions, air standards and ambient air increments, to specify the methods to be used to measure air quality and to interpret air quality data and to establish guidelines for the application of air standards. NR 404.01 HistoryHistory: Cr. Register, September, 1986, No. 369, eff. 10-1-86; corrections made under s. 13.93 (2m) (b) 7., Stats., Register, December, 1996, No. 492. NR 404.02NR 404.02 Definitions. The definitions contained in ch. NR 400 apply to the terms used in this chapter. In addition, the following definitions apply to the terms used in this chapter: NR 404.02(3)(3) “Equivalent method” means a monitoring method which has been designated as an equivalent method by the department and which has been published in a list by the department under s. NR 404.06 (4) (a). NR 404.02(4)(4) “Monitoring method” means a method for sampling and analyzing or for continuously monitoring a discrete parcel of ambient air for an air contaminant. Monitoring methods include reference methods and equivalent methods. NR 404.02(5)(5) “Primary air standard” means the level of air quality which provides protection for public health with an adequate margin of safety. NR 404.02(6)(6) “Quality assurance system” means the system of activities which provides evidence that the quality control systems are performing adequately. NR 404.02(7)(7) “Quality control system” means the system of activities which are used to control the quality of ambient monitoring or air emissions data, including all activities involved in the collection, processing and analysis of such data. NR 404.02(8)(8) “Reference method” means a method of sampling and analyzing the ambient air for an air pollutant that is specified as a reference method in 40 CFR part 50, Appendices A to N, incorporated by reference in s. NR 484.04 (2), a method that has been designated as a reference method in accordance with 40 CFR part 53, or a method that has been so designated by the department. It does not include a method for which a reference method designation has been canceled in accordance with 40 CFR 53.11 or 53.16. NR 404.02(9)(9) “Secondary air standard” means the level of air quality which may be necessary to protect public welfare from unknown or anticipated adverse effects. NR 404.02(10)(10) “Suspended particulate matter” means any solid or liquid particle dispersed and suspended in air which is capable of being trapped on the filter of a high volume air particulate sampler. NR 404.02 HistoryHistory: Cr. Register, March, 1972, No. 195, eff. 4-1-72; cr. (intro.), Register, August, 1981, No. 308, eff. 9-1-81; renum. from NR 155.01, r. (5) to (7), renum. (4) to (5) and am., am. (1) to (3), cr. (4) and (6) to (13), Register, July, 1985, No. 355, eff. 8-1-85; renum. from NR 404.01 and am. (intro.), r. (3) and (5), renum. (4) to (13) to be (3), (4), NR 400.02 (64), (5) to (10), Register, September, 1986, No. 369, eff. 10-1-86; cr. (4m) and (11), am. (8), Register, December, 1988, No. 396, eff. 1-1-89; am. (intro.), (4m), (8) and (11), renum. (1) to be NR 400.02 (5s) and am., Register, May, 1992, No. 437, eff. 6-1-92; am. (4m), (8) and (11), Register, December, 1995, No. 480, eff. 1-1-96; am. (intro.), Register, October, 1999, No. 526, eff. 11-1-99; CR 03-066: renum. (2) to be NR 400.02 (19m), am. (8) Register May 2005 No. 593, eff. 6-1-05; CR 07-082: cr. (4e) Register September 2009 No. 645, eff. 10-1-09; CR 10-050: renum. (4e), (4m) to be NR 400.02 (123e), (123s) and am. Register November 2010 No. 659, eff. 12-1-10; CR 07-082: r. (11) Register November 2011 No. 671, eff. 12-1-11. NR 404.03NR 404.03 Air quality control regions. The following air quality control regions, which include counties in Wisconsin, have been designated: NR 404.03(1)(a)(a) The Duluth (Minnesota) — Superior (Wisconsin) Interstate Air Quality Control Region includes the counties of Ashland, Bayfield, Burnett, Douglas, Iron, Price, Rusk, Sawyer, Taylor, and Washburn in Wisconsin, and the counties of Aitkin, Carlton, Cook, Itasca, Koochicing, Lake, and St. Louis in Minnesota. NR 404.03(1)(b)(b) The Southeast Minnesota — La Crosse (Wisconsin) Interstate Air Quality Control Region includes the counties of Barron, Buffalo, Chippewa, Clark, Crawford, Dunn, Eau Claire, Jackson, La Crosse, Monroe, Pepin, Pierce, Polk, St. Croix, Trempealeau, and Vernon in Wisconsin, and the counties of Blue Earth, Brown, Dodge, Faribault, Fillmore, Freeborn, Goodhue, Houston, LeSueur, Martin, Mower, Nicollet, Olmsted, Rice, Sibley, Steele, Wabasha, Waseca, Watonwan, and Winona in Minnesota. NR 404.03(1)(c)(c) The Metropolitan Dubuque Interstate Air Quality Control Region includes Grant county in Wisconsin and Clayton, Dubuque, and Jackson counties in Iowa. NR 404.03(1)(d)(d) The Rockford (Illinois) — Janesville-Beloit (Wisconsin) Interstate Air Quality Control Region includes Rock county in Wisconsin, and Boone, DeKalb, Ogle, Stephenson, and Winnebago counties in Illinois. NR 404.03(2)(a)(a) The Lake Michigan Intrastate Air Quality Control Region consists of the counties of Brown, Calumet, Door, Fond du Lac, Green Lake, Kewaunee, Manitowoc, Marinette, Marquette, Menominee, Oconto, Outagamie, Shawano, Sheboygan, Waupaca, Waushara, and Winnebago. For purposes of applying rules and regulations the Lake Michigan Air Region is divided into 2 subregions. Winnebago, Outagamie and Brown counties constitute subregion I. Calumet, Door, Fond du Lac, Green Lake, Kewaunee, Manitowoc, Marinette, Marquette, Menominee, Oconto, Shawano, Sheboygan, Waupaca, and Waushara counties constitute subregion 2. NR 404.03(2)(b)(b) The Southeastern Wisconsin Intrastate Air Quality Control Region consists of the counties of Kenosha, Milwaukee, Ozaukee, Racine, Walworth, Washington and Waukesha. NR 404.03(2)(c)(c) The Southern Wisconsin Intrastate Air Quality Control Region consists of the counties of Columbia, Dane, Dodge, Green, Iowa, Jefferson, Lafayette, Richland and Sauk. NR 404.03(2)(d)(d) The North Central Wisconsin Intrastate Air Quality Control Region consists of the counties of Adams, Forest, Florence, Juneau, Langlade, Lincoln, Marathon, Oneida, Portage, Vilas and Wood. NR 404.03 HistoryHistory: Cr. Register, March, 1972, No. 195, eff. 4-1-72; r. and recr. Register, July, 1985, No. 355, eff. 8-1-85; renum. from NR 404.02, Register, September, 1986, No. 369, eff. 10-1-86. NR 404.04NR 404.04 Ambient air quality standards. NR 404.04(1)(1) Applicability of air standards. The air standards apply to the entire state without exception. NR 404.04(2)(a)(a) Primary standard. The primary standard for sulfur oxides, measured as sulfur dioxide, is 0.075 ppm — maximum 1-hour concentration. The 1-hour primary standard is met at an ambient air quality monitoring site when the 3-year average of the annual (99th percentile) of the daily maximum 1-hour average concentrations is less than or equal to 0.075 ppm, as determined by the methodology of 40 CFR part 50, Appendix T, incorporated by reference in s. NR 484.04 (7m). NR 404.04(2)(b)(b) Secondary standard. The secondary standard for sulfur oxides, measured as sulfur dioxide, is: 0.5 ppm — maximum 3-hour average concentration, not to be exceeded more than once per year. NR 404.04(4)(4) Carbon monoxide: primary and secondary standards. The primary and secondary standards for carbon monoxide are: NR 404.04(4)(a)(a) 10 milligrams per cubic meter (9 ppm) — maximum 8-hour average concentration, not to be exceeded more than once per year. NR 404.04(4)(b)(b) 40 milligrams per cubic meter (35 ppm) — maximum 1-hour concentration, not to be exceeded more than once per year. NR 404.04(5)(5) Ozone: primary and secondary standards. The primary and secondary standards for ozone are: NR 404.04(5)(a)(a) 0.12 ppm (235 micrograms per cubic meter) — maximum 1-hour average concentration. The 1-hour ozone standards are attained when the expected number of days per calendar year with maximum hourly average concentrations above the designated level is equal to or less than one, as determined by the methodology of 40 CFR part 50, Appendix H, incorporated by reference in s. NR 484.04 (4). NR 404.04(5)(b)(b) 0.08 ppm — maximum 8-hour concentration. The 8-hour ozone standards are attained when the arithmetic mean of the fourth highest daily maximum 8-hour concentration at an ambient air quality monitoring site is less than or equal to 0.08 ppm, as determined by the methodology of 40 CFR part 50, Appendix I, incorporated by reference in s. NR 484.04 (4m). NR 404.04(5)(c)(c) 0.075 ppm — maximum 8-hour concentration. The 8-hour primary and secondary ozone ambient air quality standards are attained at an ambient air quality monitoring site when the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.075 ppm, as determined in accordance with 40 CFR part 50, Appendix P, incorporated by reference in s. NR 484.04 (6t). NR 404.04(5)(d)(d) 0.070 ppm – maximum 8-hour concentration. The 8-hour primary and secondary ozone ambient air quality standards are attained at an ambient air quality monitoring site when the 3-year average of the annual 4th-highest daily maximum 8-hour average ozone concentration is less than or equal to 0.070 ppm, as determined under 40 CFR part 50, Appendix U, incorporated by reference under s. NR 484.04 (7s). NR 404.04 NoteNote: The department promulgates ozone standards in response to federally promulgated ozone standards, and pursuant to its statutory obligation under s. 285.21 (1) (a), Stats., pars. (a) and (b) reflect standards from 1979 and 1997. They are included here to conform to the federal standards in 40 CFR part 50, where they are also included. NR 404.04(6)(a)(a) Primary standards. The primary standards for nitrogen dioxide are: NR 404.04(6)(a)1.1. 0.053 ppm — primary annual average concentration. The primary annual standard is met when the annual average concentration in a calendar year is less than or equal to 0.053 ppm, as determined by the methodology of 40 CFR part 50, Appendix S, incorporated by reference in s. NR 484.04 (7). NR 404.04(6)(a)2.2. 0.100 ppm — primary 1-hour average concentration. The primary 1-hour standard is met when the 3-year average of the annual 98th percentile of the daily maximum 1-hour average concentration is less than or equal to 0.100 ppm, as determined by the methodology of 40 CFR part 50, Appendix S, incorporated by reference in s. NR 484.04 (7). NR 404.04(6)(b)(b) Secondary standard. The secondary standard for nitrogen dioxide is 0.053 ppm. The secondary standard is attained when the annual arithmetic mean concentration in a calendar year is less than or equal to 0.053 ppm, rounded to three decimal places. Fractional parts equal to or greater than 0.0005 ppm shall be rounded up. To demonstrate attainment, an annual mean shall be based upon hourly data that are at least 75% complete or upon data derived from manual methods that are at least 75% complete for the scheduled sampling days in each calendar quarter. NR 404.04(7)(7) Lead: primary and secondary standards. The primary and secondary standards for lead and its compounds, measured as elemental lead, are the following: NR 404.04(7)(a)(a) 1.5 micrograms per cubic meter, maximum arithmetic mean averaged over a calendar quarter, as a constituent of suspended particulate matter. The primary and secondary standards for lead and its compounds, measured as elemental lead are attained when the maximum arithmetic mean averaged over a calendar quarter is less than or equal to 1.5 micrograms per cubic meter, as determined in accordance with 40 CFR part 50, Appendix B, incorporated by reference in s. NR 484.04 (3). NR 404.04(7)(b)(b) 0.15 micrograms per cubic meter – maximum arithmetic mean. The primary and secondary ambient air quality standards for lead are attained when the maximum arithmetic 3-month mean concentration for a 3-year period is less than or equal to 0.15 micrograms per cubic meter, as determined in accordance with 40 CFR part 50, Appendix R, incorporated by reference in s. NR 484.04 (6v). NR 404.04(8)(a)(a) The primary and secondary standards for PM10 are 150 micrograms per cubic meter (µg/m3) — maximum 24-hour average concentration. NR 404.04(8)(b)(b) The PM10 standards are attained when the expected number of days per calendar year with a 24-hour average concentration above 150 µg/m3, the level designated in par. (a), is equal to or less than one. NR 404.04(8)(c)(c) The expected concentrations and number of days shall be determined by the methodology contained in 40 CFR part 50, Appendix K, incorporated by reference in s. NR 484.04 (6). NR 404.04(9)(am)1.1. The primary standards for PM2.5 are 12.0 micrograms per cubic meter (µg/m3) — annual arithmetic mean concentration and 35 µg/m3 — 24-hour average concentration, measured in the ambient air as PM2.5 by either of the following methods: NR 404.04(9)(am)2.2. The primary annual standard is met when the annual arithmetic mean concentration, as determined in accordance with 40 CFR part 50, Appendix N, is less than or equal to 12.0 µg/m3. NR 404.04(9)(am)3.3. The primary 24-hour standard is met when the 98th percentile 24-hour concentration, as determined in accordance with 40 CFR part 50, Appendix N, is less than or equal to 35 µg/m3. NR 404.04(9)(bm)1.1. The secondary standards for PM2.5 are 15.0 µg/m3 annual arithmetic mean concentration and 35 µg/m3 24-hour average concentration, measured in the ambient air as PM2.5 by either of the following methods: NR 404.04(9)(bm)2.2. The secondary annual standard is met when the annual arithmetic mean concentration, as determined in accordance with 40 CFR part 50, Appendix N, is less than or equal to 15.0 µg/m3. NR 404.04(9)(bm)3.3. The secondary 24-hour standard is met when the 98th percentile 24-hour concentration, as determined in accordance with 40 CFR part 50, Appendix N, is less than or equal to 35 µg/m3. NR 404.04 NoteNote: 40 CFR part 50, Appendices L and N are incorporated by reference in s. NR 484.04 (6g) and (6r), respectively. NR 404.04 HistoryHistory: Cr. Register, March, 1972, No. 195, eff. 4-1-72; r. (1) (b)1. and 2., renum. (1) (b) 3., to be 1., Register, June, 1975, No. 234, eff. 7-1-75; am. (4), Register, August, 1981, No. 308, eff. 9-1-81; reprinted to correct error in (3), Register, November, 1981, No. 311; cr. (7), Register, April, 1983, No. 328, eff. 5-1-83; r. (5), Register, November, 1983, No. 335, eff. 12-1-83; am. Register, July, 1985, No. 355, eff. 8-1-85; renum. from NR 404.03, Register, September, 1986, No. 369, eff. 10-1-86; r. (3) (a), renum. (3) (b) to be (3) and am., cr. (8), Register, September, 1989, No. 405, eff. 10-1-89; am. (5) and (8) (b) 3., Register, May, 1992, No. 437, eff. 6-1-92; am. (5) and (8) (b) 3., Register, December, 1995, No. 480, eff. 1-1-96; am. (8) (b), Register, December, 1996, No. 492, eff. 1-1-97; CR 03-066: am. (2) (a) 1. and 2. and (b), (5) and (6), cr. (5) (b) Register May 2005 No. 593, eff. 6-1-05; CR 07-082: am. (8), cr. (9) Register September 2009 No. 645, eff. 10-1-09; CR 09-088: cr. (5) (c), (7) (a) and (b), renum. (7) to be (7) (intro.) and am. Register May 2010 No. 653, eff. 6-1-10; CR 07-082: r. (3) Register November 2011 No. 671, eff. 12-1-11; CR 15-033: am. (2) (a) (title), renum. (a) (intro.) to (a) and am., r. 1. and 2., r. and recr. (6) Register July 2016 No. 727, eff. 8-1-16; CR 16-041: am. (9) (title), cr. (9) (am) (title), consol. (9) (a) (intro.), 1., 2. and renum. to (9) (am) 1. (intro.) and am., cr. (9) (am) 1. a., b., consol. (9) (b) (intro.), 1. and renum. to (9) (am) 2. and am., renum. (9) (b) 2. to (9) (am) 3. and am., cr. (9) (bm), r. (9) (c) Register December 2017 No. 744, eff. 1-1-18; CR 21-022: cr. (5) (d) Register February 2022 No. 794, eff. 3-1-22. NR 404.05(1)(1) Scope. The ambient air increments apply to all attainment areas of the state. NR 404.05(2)(2) Class I increments. In any area of this state classified under the Act as a class I area, the ambient air increments for PM10, PM2.5, sulfur dioxide, and nitrogen dioxide may not exceed the following amounts: 1. Annual arithmetic mean 4 micrograms per cubic meter
2. Twenty-four hour maximum 8 micrograms per cubic meter
1. Annual arithmetic mean 1 microgram per cubic meter
2. Twenty-four hour maximum 2 micrograms per cubic meter
