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  2. Visibility and Haze

Final Clean Air Visibility Rule Will Restore Visibility in America's National Parks and Wilderness Areas

On June 15, 2005, EPA issued final amendments to its July 1999 regional haze rule. These amendments apply to the provisions of the regional haze rule that require emission 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 nitrogen oxides, sulfur dioxides, certain volatile organic compounds, and ammonia. The amendments include final guidelines, known as BART guidelines, for states to use in determining which facilities must install controls and the type of controls the facilities must use.

  • Final Preamble and BART Guidelines (pdf) (70 pp, 1 MB) - Federal Register, July 6, 2005. See also the the memo dated July 19, 2005 below.

The memo posted to correct errors (June 27, 2005) prior to the rule publication is available below. Also available are the rule fact sheet and the Regulatory Impact Analysis.

Note: the most recent revisions to the Regional Haze Rule were finalized in January 2017. 2017 Regional Haze Final Rule

  • Memo dated June 24, 2005 correcting errors in the rule (pdf) (82.98 KB)
  • Memo dated July 19, 2006 describing the pollutant-specific CALPUFF analysis for modeling EGU emissions and the averaging period used to estimate natural visibility background (pdf) (80.52 KB)
  • Fact Sheet - Final Amendments to the Regional Haze Rule and Guidelines for Best Available Retrofit Technology (BART) Determinations (pdf) (28.41 KB, June 2005)
  • Regulatory Impact Analysis for the Final Clean Air Visibility Rule or the Guidelines for Best Available Retrofit Technology (BART) Determinations Under the Regional Haze Regulations (pdf) (3.42 MB, June 2005, EPA-452/R-05-004)

Visibility and Haze

  • Basic Information
  • Regional Haze Program
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Contact Us About Visibility and Haze
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Last updated on May 7, 2025
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