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Visibility and Haze

Fact Sheet: Proposed Amendments To The Regional Haze Rule And Proposed Guidelines For Best Available Retrofit Technology (BART) Determinations Under The Regional Haze Rule - 2004


  • On April 15, 2004, the Environmental Protection Agency (EPA) proposed amendments to its July 1999 regional haze rule. These amendments would apply to the provisions of the regional haze rule that require emissions controls known as best available retrofit technology or BART for industrial facilities emitting air pollutants that reduce visibility. These pollutants include fine particulate matter (PM2.5), and compounds which contribute to PM2.5 formation, such as oxides of nitrogen, sulfur dioxides, and certain volatile organic compounds.

  • The BART requirements of the regional haze rule apply to facilities built between 1962 and 1977 that have the potential to emit more than 250 tons a year of visibility-impairing pollution. Those facilities fall into 26 categories, including utility and industrial boilers, and large industrial plants such as pulp mills, refineries and smelters. Many of these facilities previously have not been subject to federal pollution control requirements for these pollutants.

  • Under the 1999 regional haze rule, states are required to set periodic goals for improving visibility in the 156 natural areas. As they work to reach these goals, states must develop "implementation plans" that contain enforceable measures and strategies for reducing visibility-impairing pollution. States must develop their implementation plans by January, 2008. States will need to identify the facilities that will have to install BART controls, and must support their decisions in their implementation plans.

  • The BART requirement directs state air quality agencies to identify whether emissions from sources subject to BART are well controlled, or whether retrofit measures are available to reduce the emissions below current levels. For some of the source categories, existing technology often can reduce emissions by up to 90 to 95 percent. Implementation of this proposal would result in reductions of 2.2 million tons of sulfur dioxide and 1.2 million tons of nitrogen oxides from the power sector by 2015.

  • The proposed amendments would not set federal emission limits for these plants; states will set those limits as they implement the regional haze rule. Today's amendment also proposes guidelines, known as BART guidelines, for states to use in determining which facilities must install controls and the type of controls they must use.

  • According to the Clean Air Act, as states conduct BART determinations for individual facilities, they must consider a number of factors, including:
    1. the cost of the controls;
    2. the impact of controls on energy availability or any non-air quality environmental impacts;
    3. the remaining useful life of the equipment to be controlled;
    4. any existing pollution controls already in place; and
    5. the visibility improvement that would result from controlling the emissions.

  • These factors may lead states to use the best technology available, a less-effective technology, or none at all. The proposed guidelines includes information to help states evaluate these issues.

  • The proposed guidelines also explain:
    1. How to identify the plants and equipment for which a BART analysis is required;
    2. The circumstances under which a source may avoid a detailed BART review;
    3. The procedures for reviewing available emission control methods, and procedures for summarizing and reporting the results of this review; and
    4. The type of air quality analysis that EPA requires in the regional haze regulation.

  • Today's proposed rule also provides guidelines for states that want to establish an emissions trading program, an alternative to BART allowed under the haze rule. States may use such cost-effective trading programs, provided they yield greater visibility improvement and emissions reductions than would be expected through emission controls on each facility.

  • EPA will take public comment on the proposal for 60 days after it is published in the Federal Register. EPA will consider public comment before finalizing this rule by April 15, 2005.


  • To reduce haze, and to meet requirements of the Clean Air Act, EPA in April 1999 issued a regional haze rule aimed at protecting visibility in 156 federal areas. The rule seeks to reduce the visibility impairment caused by many sources over a wide area. EPA's previous visibility regulation, issued in 1980, addressed only local visibility impairment from local sources.

  • Soon after the regional haze rule was finalized, several parties filed petitions to challenge the rule with the U.S. Court of Appeals for the D.C. Circuit.

  • Because regional haze is a problem caused by multiple sources over a wide area, EPA's rule required states in determining BART requirements to analyze visibility impacts from multiple sources rather than on a source-by-source basis. In May 2002, the court ruled that EPA's specific approach to this issue was not consistent with the Clean Air Act.

  • This proposed rule is in response to the May 2002 ruling by the U.S. Court of Appeals for the D.C. Circuit vacating parts of the BART provisions of the regional haze rule (American Corn Growers et al. v. EPA, 291 F. 3d 1 (D.C. cir. 2002)).

  • EPA initially proposed BART guidelines on July 20, 2001, but did not finalize that proposal, in light of the Court ruling.

  • When compared to the 2001 proposal, this proposal would require states to consider the visibility impacts of an individual facility when determining whether they have to install controls, and what those controls would be.

  • The other change of note is with the presumptive levels of controls for large electric generating units. This proposal would add an emissions standard for nitrogen oxides that was not included in the 2001 guidelines, and would refine the emissions standard for sulfur dioxide. Other changes are relatively minor clarifications in response to comments received.

  • During much of the year, a veil of white or brown haze hangs over many of the country's most visited natural areas, obscuring some of the nation's most famous scenic vistas. This haze - caused primarily by tiny particles that absorb and scatter sunlight - is a result of air pollution from power plants, cars and factories that travels hundreds of miles to some of the country's most remote lands.

  • The same pollution that causes haze also poses serious health risks, especially for people with chronic respiratory diseases.