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    One of the most basic forms of air pollution, haze, occurs when light is scattered by particles and gases in the air. Although some haze occurs naturally, like windblown dust and soot from wildfires, most of these particles and gases are a result of man's activities and are from sources such as electric power generation, industrial processes, mobile emissions, agricultural burning, and construction. Visibility impairing pollutants include sulfates, the largest contributor on the east coast, as well as oxides of nitrogen (NOx), light absorbing carbon, organic carbon, soil, and coarse material. Haze reduces the visibility in our cities and scenic areas. Even remote areas can be affected due to transport of pollutants by the wind many hundreds of miles. Visibility in Pennsylvania, without pollution, would ordinarily be about 90 miles. Currently, it is only around 15-25 miles. The pollutants creating haze can also be detrimental to the health of Pennsylvanians.

    What is being done to reduce haze?

    In the 1977 Clean Air Act amendments, Congress added Section 169A (42 U.S. Code § 7491) which set forth a national goal of achieving natural visibility conditions. The U.S. Environmental Protection Agency (EPA) published the Regional Haze Rule in 1999 (64 FR 35714) with amendments in 2005 (70 FR 39104) and 2017 (82 FR 3078). The Regional Haze Rule calls for state and federal agencies to work together to improve visibility in 156 Class I Federal areas (commonly referred to as “Class I areas”), which includes many our nation’s national parks and wilderness areas, and sets a national goal for natural visibility conditions by 2064.

    What does regional haze mean for Pennsylvania?

    Although Pennsylvania does not have any Class I areas within its borders, emissions from this Commonwealth affect visibility in Class I areas in other states. The rule requires states, in coordination with EPA, Federal Land Managers (U.S. National Park Service, U.S. Fish and Wildlife Service and U.S. Forest Service) and other interested parties to develop and implement air quality plans to reduce the pollution that causes visibility impairment.

    All states, even those such as Pennsylvania that do not contain a Class I area, are required to address the contribution from sources in their state to regional haze in Class I areas that they affect. Although the goal of the Regional Haze Rule is a return to natural visibility in the Class I areas, visibility throughout the region will improve as a result of the actions taken under this rule. The same particles that degrade visibility also have been linked to serious health effects and environmental effects such as acid rain and stream eutrophication. Therefore, actions taken to improve visibility can also be expected to benefit public health and reduce certain adverse effects to the environment.

    States are responsible for developing a Regional Haze State Implementation Plan (SIP) that addresses regional haze in each Class I area located within the state (if applicable) and in Class I areas located outside the state which may be affected by emissions from sources within the state. The Regional Haze SIP is required to identify and analyze sources that cause or contribute to visibility impairment and demonstrate reasonable progress toward reaching visibility goals. States are also responsible for periodic comprehensive updates to their Regional Haze SIPs.

    States are also responsible for providing interim progress reports that outline the status of the required Regional Haze SIP elements. These progress reports are generally due every five years after a state submits its SIP. The progress reports evaluate how the state is moving towards the visibility goals for each Class I area to assess whether or not changes to the state’s Regional Haze SIP are needed to achieve these goals.

    Pennsylvania is part of a consortium made up of northeastern and mid-Atlantic states, tribes, and federal agencies, known as the Mid-Atlantic/Northeast Visibility Union (MANE-VU) Regional Planning Organization. MANE-VU states work together to develop and coordinate regional haze planning activities.

    First Implementation Period (2002 – 2018)

    The first implementation period for Regional Haze covers the years 2002 through 2018. Specific to the first implementation period, the regulations required the application of Best Available Retrofit Technology (BART) to certain sources in 26 categories (PDF) that were installed between 1962 and 1977 that have the potential to emit more than 250 tons per year of a visibility impairing pollutant.

    MANE-VU developed what is commonly referred to as the 2007 MANE-VU “Ask” (PDF). The 2007 MANE-VU “Ask” presents a course of action to pursue the adoption and implementation of five strategies in order to assure reasonable progress.

    The final SIP revision addresses the Regional Haze requirements, including the following: (1) the net effect on visibility resulting from changes from the 2002 base-year inventory projected by 2018 in point, area and mobile source emissions; (2) the reasonable progress goals for affected Class I areas; (3) the Guidelines for BART Determinations; and (4) the Commonwealth's long-term strategy, which includes enforceable emissions limitations, compliance schedules, and other measures as necessary to achieve the reasonable progress goals. This SIP revision addresses the 2007 MANE-VU “Ask” and demonstrates how the Commonwealth's emission control strategies, when coordinated with other state and tribes' strategies, is sufficient to meet or exceed the reasonable progress goals for affected Class I areas and improve visibility. The Regional Haze SIP revision was initially submitted to EPA for approval on December 20, 2010. Pennsylvania’s initial Regional Haze SIP, Cheswick SIP revision, Five-Year Progress Report SIP revision and BART SIP revision are available on the State Implementation Plan page under “Non-Regulatory SIP Revisions”, “Reducing Regional Haze”.

    Second Implementation Period (2018 – 2028)

    The second implementation period for Regional Haze covers the years 2018 through 2028. The Commonwealth's second Regional Haze SIP revision is due by July 31, 2021.

    In 2017, MANE-VU developed strategies for the second implementation period. The 2017 MANE-VU “Ask” (PDF) presents a course of action to pursue the adoption and implementation of six “emission management” strategies in order to assure reasonable progress.

    The final SIP revision will address the Regional Haze requirements, including the following: (1) the net effect on visibility projected emissions to 2028; (2) the reasonable progress goals for affected Class I areas; (3) 4-factor analysis determinations; and (4) the Commonwealth's long-term strategy. This SIP revision will also address the 2017 MANE-VU “Ask” and demonstrate how the Commonwealth's emission control strategies, when coordinated with other state and tribes' strategies, is sufficient to meet or exceed the reasonable progress goals for affected Class I areas and improve visibility.

    More Information

    EPA Information