WASHINGTON— A federal judge has approved a legal agreement requiring the Environmental Protection Agency to finalize plans for cleaning up unhealthy sulfur dioxide air pollution in four areas of Texas and Tennessee.

The agreement, which was approved on Wednesday, includes steps to reduce harmful levels of the pollution in areas where more than 30,000 people live in the two states. Sulfur dioxide can trigger asthma attacks and cause damage to lungs and the cardiovascular system that can be fatal. It also contributes to acid rain and haze.

“For too long the Trump EPA’s illegal delay in tackling sulfur pollution has poisoned the air thousands of people breathe,” said Jeremy Nichols, a senior advocate at the Center for Biological Diversity. “This agreement is an important step toward reducing the harms caused by this administration’s reckless habit of violating the law to benefit large industrial polluters.”

The Clean Air Act requires the EPA to set air quality standards that apply nationwide to protect people and the environment from pollutants like sulfur dioxide. When those standards are violated, the agency must ensure that states have valid plans in place to clean up the pollution.

“Sulfur pollution contributes to heart and lung diseases and is particularly dangerous for children and the elderly,” said Zachary Fabish, a Sierra Club attorney. “Getting plans in place to reduce this pollution should be an agency priority, but EPA delay has become all too routine.”

Power plants are the largest source of sulfur dioxide air pollution. Other major emitters include industrial processes like extracting metal from ore and oil refining, along with fossil-fuel burning ships, vehicles and heavy equipment.

Sources of sulfur dioxide in the affected areas include coal-burning boilers in Tennessee and oil refineries in Texas.

Pollution associated with sulfur dioxide causes a range of public health and environmental problems. According to the EPA, exposure can harm a person’s health in as little as five minutes.

Sulfur dioxide also contributes to acid rain and haze, damaging lakes, streams and ecosystems throughout the United States and decreasing visibility in national parks.

The Center for Biological Diversity and Sierra Club sued Trump’s EPA in August 2025 after the agency missed its deadlines to finalize plans for cleaning up sulfur dioxide pollution in Texas and Tennessee.

This lawsuit, filed in the U.S. District Court for the Northern District of California, is part of the two groups’ ongoing work to compel the EPA to protect human health and the environment from sulfur dioxide pollution in accordance with the Clean Air Act’s requirements.

More information about the fight against air pollution is available at Protecting Air Quality Under the Clean Air Act.