Class I Prevention of Significant Deterioration
National Air Quality Standards
The Clean Air Act of 1970 set National Ambient Air Quality Standards (NAAQS) across the United States. To further protect public health and welfare, environmental health, and preserve and protect air quality, the Prevention of Significant Deterioration (PSD) program was included in amendments to the Clean Air Act in 1977.
More information on NAAQS
The goal of the PSD program is to protect public health and welfare from the adverse effects of increased air pollution. The PSD program works to achieve these aims while ensuring that economic growth occurs in harmony with the preservation of air quality. PSD provisions do not affect current air emissions, the provisions are designed to prevent significant deterioration from baseline air quality.
Prevention of Significant Deterioration Classifications
The PSD program created three classifications:
| Class I | Class II | Class III |
| -Allows for minimal degradation of air quality -158 federal areas -5 tribal areas | -Allows for a moderate increase of air pollution -All US lands unless otherwise designated or re-designated | -Allows for the greatest increase in air pollution -No lands have been redesigned as Class III |
Prevention of Significant Deterioration Program Criteria
The PSD program contains specific criteria for determining which areas were federally-mandated as Class I by the Clean Air Act. Criteria was also set for areas that may be redesignated from Class II to Class I at a later date.
40 CFR § 52.21
| Federal Mandatory Class I Areas (cannot be re-designated to class II or class III) | Areas that May be Re-designated to Class I (Non-mandatory) |
| – International Parks Exist on/ before August 7th 1977 –National Wilderness Exist on/ before August 7th 1977 and larger than 5,000 acres in size –National Memorial Parks Exist on/ before August 7th 1977 and larger than 5,000 acres in size –National Parks Exist on/ before August 7th 1977 and larger than 6,000 acres in size | –National Monument –National Primitive area -National Preserve -National Recreational area -National Wild and Scenic River -National Wildlife Refuge -National Lakeshore or Seashore Larger than 10,000 acres in size on August 7th 1977 -National Park -National Wilderness area Established after August 7th 1977 and larger than 10,000 acres in size -State Land Areas deemed appropriate by State land managers –Tribal Reservation Land Areas deemed appropriate by Tribal Government |
A Venn diagram better shows what kinds of areas have been mandated as Class I areas and which areas may be re-designated as Class I areas
Federal Class I Areas
The Prevention of Significant Deterioration (PSD) program set all land in the United States as Class II and created 158 Federal Class I areas that met the outlined requirements. These Federal Class I areas are administered by the National Park Service, the U.S. Forest Service, and the U.S. Fish and Wildlife Service.
Non-Federal Class I Areas
At this time, all state lands have remained as Class II. Five tribal reservations have been redesignated from Class II to Class I since 1977. For more information on these tribal redesignations, please see the information compiled on this page: Forest County Potawatomi Community’s Class I for Tribes
Redesignating an Area as a Different Class
The PSD program mandated certain federal Class I areas when initially passed by Congress. In addition, the PSD program allows for States and Tribal Nations to redesignate areas from Class II to Class I or Class III. The redesignation procedure is described in 40 C.F.R. § 52.21.
Prevention of Significant Deterioration Increments
Increments in Class II and Class I areas are triggered by submission of the first PSD preconstruction permit application from a major new or modified source (Clean Air Act § 163). PSD provisions allow a modest increase in Class II areas, while allowing a smaller increase in Class I areas. Class I ensures economic growth will occur in a manner consistent with the preservation of existing clean air resources.
National Ambient Air Quality Standards were set nationwide by the Clean Air Act in 1970. Class III, II, and I increments were set in the 1977 Amendments and are separate from the NAAQS.
Increments are a maximum allowable increase in the concentration of a pollutant above baseline. Baseline is the level of air quality before the first large air pollution source moves into the area. Increments only apply to the three pollutants designated in the PSD program – sulfur dioxide, nitrogen dioxide, and particulates.
Wisconsin DNR minor source baseline dates (Feb 2014)
Prevention of Significant Deterioration Allowable Increments
40 CFR 52.21(c)
Wisconsin NR §405.05
Major Sources and Permits
To obtain a permit, major new and modified sources must:
- install “best available control technology”
- analyze all impacts of the proposed source’s emissions
- together with emissions from “secondary growth” associated with the source
- as well as emissions from already existing and permitted sources
- not violate the National Ambient Air Quality Standards
- not violate a PSD Increment
- not have an adverse impact on a Class I area
- may have to conduct preconstruction (and possibly post-construction) monitoring of air quality
- must assure no adverse impact on the Class I area’s visibility if there is potential to affect the visibility of a Class I area
U.S. EPA Region 5 Air Permits
Class I Areas in the Western Great Lakes Region
For more information, click each Class I area on the map to go to each Class I area’s website (you will be directed to the relevant land manager’s website – either National Park Service, U.S. Forest Service, U.S. Fish and Wildlife Serive, or the Forest County Potawatomi Community).
Class I PSD Redesignation
National Ambient Air Quality Standards were set across the United States in the Clean Air Act of 1970. To further protect public health and welfare, environmental health, and preserve and protect air quality, the Prevention of Significant Deterioration (PSD) program was included in amendments to the Clean Air Act in 1977.
The goal of the PSD program is to protect public health and welfare from the adverse effects of increased air pollution. The PSD program works to achieve these aims while ensuring that economic growth occurs in harmony with the preservation of air quality. PSD provisions do not affect current air emissions, the provisions are designed to prevent significant deterioration from baseline air quality.
Class I PSD Redesignation Procedure
The PSD program mandated certain federal Class I areas when initially passed by Congress. In addition, the PSD program allows for States and Tribal Nations to redesignate areas from Class II to Class I or Class III. The redesignation procedure is described in 40 C.F.R. 52, § 52.21.
40 CFR 52.21
- Hold at least one public hearing before submitting the re-designation request
- Notify states, other tribes, and federal land managers of areas that may be affected by the re-designation at least 30 days before the hearing
- Consult with local and other sub-state general purpose governments in the area (e.g. cities, counties, local agencies)
- Prepare a description and analysis of health, environmental, economic, social, and energy effects of the proposed reclassification that must be made available for public review at least 30 days before the required public hearing
Bad River Class I PSD Re-designation
The Bad River Band of Lake Superior Chippewa notified the U.S. EPA of its intent to redesignate the air quality status on the Bad River Reservation in northern Wisconsin from Class II to Class I. This proposed change will help the Tribe protect its air quality and allow the Tribe to develop land use plans that are compatible with Tribal cultural beliefs and its renewable resources.
Bad River Class I PSD Re-designation Documents
Documents concerning the redesignation of the Bad River Reservation are available as digital documents. Click the PDF icon to open the document, or right-click to download the file.
Locations of the Class I Redesignation Analysis document
Printed copies of the Class I Analysis document have been placed in libraries surrounding the Bad River Reservation. The following libraries each have a copy of the document for public review:
- Bad River Library, Chief Blackbird Building, Odanah, Wisconsin
- Hurley Public Library, Hurley, Wisconsin
- Madeline Island Public Library, La Pointe, Wisconsin
- Vaughn Public Library, Ashland, Wisconsin
- Washburn Public Library, Washburn, Wisconsin
- Legion Memorial Library, Mellen, Wisconsin
Please click the name of each library to be directed to that library’s website to obtain the library’s address and hours of operation.