Air Resource Management Program - Clean Air Act
The Clean Air Act sets standards for air quality to protect public health and welfare. The Forest Service must ensure that its activities, or activities it permits, comply with these national standards and any state and local requirements for air pollution control. Each state outlines how it will implement Clean Air Act requirements in its State Implementation Plans.
The Clean Air Act also allowed the Environmental Protection Agency to establish national air quality standards to protect public health and welfare. The Act Amendments of 1977 established the Prevention of Significant Deterioration program which established Class I areas and charged the Forest Service as one of three federal land managers responsible. State legislation and Prevention of Significant Deterioration regulations determine how the air quality regulatory process is conducted state by state.
Resources:
Regulatory and Guidance Information by Topic: Air (Environmental Protection Agency)
Overview of the Clean Air Act and Air Pollution (Environmental Protection Agency)
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Prevention of Significant Deterioration
Prevention of Significant Deterioration is a state-permitting process that requires emission limitations for certain new or modified sources of air pollution, mandated by the Clean Air Act Amendments of 1977.
The Forest Service has input into this permitting process by providing comments to air regulatory agencies on potential source impacts to sensitive air pollution receptors, also termed air quality related values.
Resources:
Environmental Protection Agency
42 U.S. Code § 7491 - Visibility protection for Federal class I areas (Cornell Law School)
Subpart D—Identification of Mandatory Class I Federal Areas Where Visibility Is an Important Value (Code of Federal Regulations)
Federal Class I Areas
Air quality can be designated in three ways based on the National Ambient Air Quality Standards. Attainment areas are those that meet or are cleaner than the national standards, while nonattainment areas are those that don’t meet the national standard. If the Environmental Protection Agency is unable to determine an area’s status after evaluating the available information, those areas are designated “unclassifiable.”
Under this program, attainment areas are categorized as either Class I, Class II, or Class III based on their levels of air quality protection. According to the Environmental Protection Agency, Class I allows very little deterioration of air quality, Class II allows moderate deterioration, and Class III allows more deterioration. In all cases, the pollution concentrations shall not violate any of the National Ambient Air Quality Standards.
The Clean Air Act established Class I areas in each national park over 6,000 acres and each national wilderness larger than 5,000 acres that existed when the 1977 Amendments were passed. They have the most stringent degree of protection from future degradation of air quality.
The National Park Service, Fish and Wildlife Service, and Forest Service are the three federal land managers of Class I areas. The Forest Service manages 448 wilderness areas and works to protect air quality related values in the 88 Class I areas. All other areas are Class II. The list below contains all Class I areas managed by the Forest Service and their air quality related values (AQRVs). View the complete list of Class I areas.
Class I Wilderness Areas Managed by the Forest Service
Explore Class I areas using this interactive wilderness map. Use the pop-ups on the map to learn more about each wilderness area, including natural background visibility data, photos and maps, and resource concern thresholds for several air quality related values.
Air Quality Related Values
The Clean Air Act directs federal land managers to determine those features of a national wilderness area that are sensitive to air pollution. Sensitive features of the wildernesses are known as air quality related values. Monitoring air quality related values determine ecosystem health related to air pollution impacts and gathers background data for the Prevention of Significant Deterioration permit process. In addition to monitoring values, air chemistry, and atmospheric deposition monitoring are necessary to establish linkages between air pollution and any changes to the physical, chemical, or biological condition of the sensitive receptors. A sensitive receptor is an attribute of an air quality related value first affected by air pollution, while a sensitive receptor indicator is how the receptor can be measured. See the table below for examples.
| AQRV | Sensitive Receptor | Sensitive Receptor Indicator |
|---|---|---|
| Flora | Lichens | Metal concentration |
| Visibility | Scenic vista | Haziness |
| Water | Water chemistry | Acid neutralizing capacity |
The Prevention of Significant Deterioration process aids in the protection and enhancement of air quality in national wilderness areas and other locations of scenic, recreational, historic, or natural value. If a new air pollution source is required to receive a Prevention of Significant Deterioration permit, it must do so before beginning construction. The Forest Service manager must be consulted by the state on projects that, "may affect” any Forest Service Class I area. When reviewing the application, the manager must make three decisions:
What are the sensitive air pollution receptors and air quality related values within the wilderness that need protection?
What are the concern thresholds for these receptors?
Will the proposed facility cause or contribute to pollutant concentrations or atmospheric deposition within the wilderness that will cause the thresholds to be exceeded?
The first two decisions are land management issues based on the management goals for the wilderness in question. The third is a technical question analyzed by models combining proposed emissions, background levels of pollutants, and the sensitivity of visibility and resources to the pollutants.
The Forest Service reviews the air permit applications for new and modified industrial facilities to ensure their air emissions will not adversely impact the air quality related values of federally protected wilderness areas. The Forest Service provides these comments to the permitting authority.
Close coordination between the Forest Service and the appropriate air regulatory agency is essential in the Prevention of Significant Deterioration process. The Forest Service decides whether a proposed project will adversely impact National Forest System lands. The air regulatory agency then decides to grant or deny the requested permit. The Forest Service, National Park Service, and U.S. Fish and Wildlife Service formed the Federal Land Managers’ Air Quality Related Values Work Group to consistently evaluate air pollution effects on air quality related values and to provide state permitting authorities and potential permit applicants the same guidance regarding the assessment of new source impacts on air quality related values. Read the 2010 Work Group guidance.
Best Available Control Technology (New or Modified Pollutant Sources)
An important part of the Prevention of Significant Deterioration permit application is a review of the air pollution control technologies proposed for new or modified emission units at the facility. The Prevention of Significant Deterioration regulations assumed requiring pollution control implementation at the time of new source construction or modification upgrades would lead to the most cost-efficient implementation of control technologies by forcing facility owners to incorporate the control implementation costs into the design costs.
In general, reviewing air pollution control technology involves an analysis of the control technologies available for each regulated pollutant and its source units. The best-performing option is recommended unless it is deemed too expensive or causes other adverse environmental impacts.
This process ensures that the best available control technology is applied to industrial sources, thus reducing air emissions to the lowest possible amount, and minimizing air pollution impacts on the national forests.
Regional Haze Rule
The Regional Haze Rule of 1999 requires states and interested tribes to address sources of pollution contributing to regional haze in the 156 mandatory Class I areas. States develop State Implementation Plans to demonstrate to the public, the federal land managers, and the Environmental Protection Agency how they plan to make progress on addressing regional haze. These plans are developed in 10-year increments to reach natural background conditions by 2064. The Environmental Protection Agency defines natural background as conditions due only to non-anthropogenic sources.
The Forest Service, as a federal land manager of Class I areas, works closely with the states, interested tribes, the Environmental Protection Agency, and the Regional Planning Organizations in the development of the technical products and policy documents that are used by each state as they develop and modify their plans. By law, the federal land manager of Class I areas has a formal consultation with each state 60 days before draft plans go to public hearing. As stewards of the resource targeted for protection, the Forest Service has a special duty to ensure the Class I areas under our jurisdiction are managed for the use and enjoyment of current and future generations.
Resources
Visibility and Regional Haze (Environmental Protection Agency)
General Conformity Rule
The General Conformity Rule ensures that federally funded or supported actions taken by federal agencies and departments, including the Forest Service, meet national standards for air quality in federal nonattainment and maintenance areas. Under the Clean Air Act, a nonattainment area is any area that violates national ambient air quality standards for any of the six criteria pollutants. These pollutants are sulfur dioxide, particulate matter, carbon monoxide, ozone, nitrogen dioxide, and lead. Maintenance areas are former nonattainment areas that have been redesignated to attainment status and may require special measures to maintain their attainment status.
Activities that emit significant levels of criteria pollutants in a nonattainment or maintenance area are subject to the conformity rule. This rule requires the Forest Service or any federal agency to demonstrate that their action will not impede the State Implementation Plans to attain or maintain the ambient air quality standard. Examples of activities on national forests and grasslands that may require a review for conformity include:
Oil, gas, or mineral mining development
Fuel treatments, including prescribed fire and harvest activities
Road, trail, or building construction
Land use and special use permit decisions, such as ski or winter sports areas and landfills
Resources
General Conformity (Environmental Protection Agency)
State Smoke Management
Most states have developed plans for managing and controlling smoke from prescribed fires. A smoke management program is designed to minimize smoke entering populated areas, prevent public safety hazards (such as smoke on roads or runways), avoid national ambient air quality violations, and avoid visibility impacts on Class I areas. Smoke Management Plans may be part of the State Implementation Plan.