Press Release May 12, 2021

Parks Group’s Report Finds Flawed Methods and Modeling Fails to Identify 90 Percent of Southeastern Sources Polluting Air in National Parks and Communities

Due to the flawed information, Southeastern states are on track to ignore more than 300 sources of pollution. 

Washington, DC – A report issued today by the National Parks Conservation Association (NPCA) found major flaws in an air pollution model and methods being used by ten Southeastern states. Due to the flawed information, Southeastern states are on track to ignore more than 300 sources of pollution, which would allow more than 500,000 tons of harmful emissions to continue dirtying the air in our national parks and communities. Additionally, nearly 90 percent of these unidentified sources are in communities living below the poverty line.

The independent report, commissioned by the NPCA, analyzed an air pollution model and methods from the Visibility Improvement State and Tribal Association of the Southeast (VISTAS), a Regional Planning Organization supporting the development of Regional Haze State Implementation Plans in ten Southeastern states, as well as the Eastern Band of Cherokee Indians, and Knox County, TN. NPCA is now urging these states to not solely rely on the VISTAS model and methods in the development of their haze plans and assess additional sources of pollution for emission reduction measures.

“An entire region of the United States is relying on a flawed model and methods to create critical plans meant to reduce haze pollution in our national parks and communities,” said Ulla Reeves, Senior Advocacy Manager for NPCA’s Clean Air Program. “Southeastern states plan to ignore hundreds of sources, from coal plants to oil and gas development, that are polluting the air we breathe, putting the health of our parks and communities at risk, and driving the climate crisis. These regional haze plans are a once-in-a-decade opportunity for states to address air pollution and we cannot allow states to rely on inaccurate data to get us there.”

NPCA’s analysis identified numerous and substantial issues in the VISTAS methods, which Southeastern states are relying on to inform plans that are meant to reduce pollution to improve air quality and visibility in national parks. These issues affected the model’s outcome and drastically reduced the number of sources identified for emission reductions. Key takeaways from the analysis include:

  • While NPCA has identified 342 sources in the Southeast region potentially impairing visibility in national parks and wilderness areas, the VISTAS model set such high thresholds that it only identified 33 sources of pollution.
  • VISTAS modeling did not accurately reflect the contribution of power plant emissions to visibility impairment in national parks and wilderness areas across the Southeast region. NPCA’s analysis identified 56 power plants potentially affecting visibility in parks, but VISTAS model identified only 14.
  • The VISTAS modeling used decade-old data that does not accurately reflect the dramatic increase in nitrate pollution and significantly miscalculates sulfate pollution, both of which contribute to visibility impairment in national parks and communities across the Southeast region and directly harm humans, animals and plants.

“The Southeast region is home to some of our country’s most iconic and majestic national parks and wilderness areas, from the Everglades in Florida to Mammoth Cave in Kentucky to Sipsey Wilderness Area in Alabama.” said Phil Francis, Chairman of the Coalition to Protect America’s National Parks. “Poor air quality not only affects the health of park ecosystems, it also directly harms visitation and local economies that depend on parks to support thousands of jobs across the region. Southeastern states must step up and do the right thing for our parks and communities that rely on them for a living.”

The Regional Haze Rule mandated by the Clean Air Act is a time-tested, effective program that requires federal and state agencies to evaluate measures and work together to restore clear skies at protected national parks and wilderness areas around the country, including four national parks (Great Smoky Mountains, Everglades, Mammoth Cave and Shenandoah) and 14 Wilderness Areas in the Southeast. Currently, all 50 states are in the process of developing their next round of plans to submit to the Environmental Protection Agency, specifying the pollution reducing measures they will implement to improve air quality and visibility in parks. The VISTAS modeling effort was conducted to assist Southeastern states in the development of these plan.

“The outdoor industry knows all too well that poor air quality is bad for business,” said Will Harlan, Senior Editor for Blue Ridge Outdoors Magazine. “Studies show that when air quality is low, park and wilderness area visitation drops, so our industry relies on clean air to ensure that people can safely enjoy natural lands. Our industry needs strong indications from states that they are committed to restoring clean air so that the public feels safe to recreate outdoors.”

“It is critical that we restore clean air and protect public health, especially for our most vulnerable populations,” said Dr. Stephanie Johannes, Health Program Manager for Clean Air Carolina. “Children are particularly vulnerable to the effects of haze-related pollution as it’s linked to illness throughout childhood from low birth weight and infant mortality to asthma. Older people and those with heart and lung conditions are also at greater risk, but even healthy adults are at risk when haze pollution is high.”

NPCA, along with Sierra Club and Southern Environmental Law Center sent a letter to ten Southeastern states expressing our concerns with their planning processes and reliance on the VISTAS model and methods. The letter also urges states to revisit their approach to ensure their obligations to restore clear skies in our parks is met in their haze plans.

The full independent analysis can be found here and a summary of the report, highlighting key takeaways can be found here.

NPCA continues to work directly with state agencies and lawmakers, providing data and expertise, and helping to secure strong state plans to limit haze pollution.


About the National Parks Conservation Association: Since 1919, the nonpartisan National Parks Conservation Association (NPCA) has been the leading voice in safeguarding our national parks. NPCA and its nearly 1.6 million members and supporters work together to protect and preserve our nation’s most iconic and inspirational places for future generations. For more information, visit

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