Resource Apr 17, 2023

Regional Haze Pollution in EPA Region 4

Strong state regional haze plans are critical to restoring clean air and clear skies to treasured places like Great Smoky Mountains National Park and Okefenokee National Wildlife Refuge. Unfortunately, states in the Southeast are failing to adequately cut air pollution impacting these parks and wilderness areas and communities.

Average Visibility in Miles

Everglades Visibility

Smoky Mountains Visibility

[epa haze region] region 4 map

Sources of Haze Pollution in the Southeast

(Click image to enlarge)

There are 156 national parks and wilderness areas designated under the Clean Air Act as “Class 1 areas,” meaning they have some of the highest levels of air quality protection in the country. However, most national park sites are still experiencing poor air quality and diminished visibility.

In the Southeast, Mammoth Cave National Park was found to be the most haze polluted park in the country in an analysis done by NPCA. Great Smoky Mountains National Park ranked the second most haze polluted, and Everglades National Park came in sixth.

The Regional Haze Rule is intended to cut pollution harming skies in these special places. Every ten years, each state must develop a plan to reduce haze-causing emissions from pollution sources within their state. The state agencies then send these plans to the U.S. Environmental Protection Agency (EPA) for approval or disapproval.

As of May 2023, Georgia, South Carolina, North Carolina, Florida and Tennessee have submitted haze plans to EPA. Kentucky, Alabama, and Mississippi have yet to submit plans. All Southeast states are relying on a shared, flawed modeling system, through VISTAS, in developing their haze plans. In relying on the VISTAS approach, states in the Southeast are completely ignoring nitrogen oxide (NOx) emissions and huge polluters across the region that harm air quality in our parks and wilderness areas. Read more in our report here.


In the first round of regional haze planning over ten years ago, significant emissions reductions were achieved thanks in large part to advocacy efforts for strong state plans. 1.4 million tons of haze pollution (nitrogen oxides, sulfur dioxide, and particulate matter) each year were eliminated, along with 79 million tons of climate pollution (carbon dioxide, methane, and nitrous oxide). 146 coal plants were required to either close or clean up.


The second round of haze planning is currently in progress, and many states around the country are proposing haze plans that do not cut emissions or lead to reasonable progress in reducing haze pollution in our parks. Haze plans that allow polluters to go unchecked put our parks and wilderness areas at stake, along with sensitive ecosystems, public health, and local tourism economies.


Haze pollution is also an issue of environmental justice, as many haze polluters are located in close proximity to overburdened communities. The EPA has directed states, through their haze plans, to take into consideration the intersection of people’s health and historic inequities. Many, if not most, states have not done this. NPCA will continue advocacy to EPA to ensure haze plans capitalize on the opportunity to clean up air for communities that have suffered the brunt of pollution for far too long.

Read more from NPCA