WASHINGTON— The Center for Biological Diversity and Sierra Club filed a lawsuit today challenging the Environmental Protection Agency’s failure to ensure that counties in three states have effective plans for cleaning up sulfur dioxide air pollution.

Approximately 40,000 people in Arizona, Tennessee and Texas live in the areas at issue in this lawsuit, with sulfur dioxide pollution at levels that harm human health and the environment.

“The Trump EPA’s needless, illegal delay in tackling sulfur pollution is poisoning the air that thousands of people breathe,” said Ryan Maher, an attorney at the Center for Biological Diversity. “It’s a brazen handout to big industry polluters and fossil fuel companies, sacrificing the health of vulnerable people for corporate profits.”

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

“This pollution harms people in the worst ways possible,” said Zachary Fabish, a Sierra Club attorney. “It’s imperative that Trump’s EPA uphold its duty to protect the public’s health by acting immediately, as the law requires.”

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

The primary sulfur dioxide sources at issue in the affected areas include a copper smelter in Arizona, a chemical manufacturing plant 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, triggering asthma attacks and damage to the lungs and cardiovascular system that can be fatal.

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

Today’s lawsuit, filed in the United States 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.