OAKLAND, Calif.— Environmental and public-health groups filed notice today of their intent to sue the Environmental Protection Agency for failing to ensure that effective plans are in place to reduce dangerous soot air pollution in Los Angeles and Imperial County, California.

The groups also notified the EPA of their intent to sue over the agency’s delayed decision on whether soot pollution in Imperial County, Plumas County, California and Allegheny County, Pennsylvania continues to exceed the EPA’s legal limit. If the pollution is still above the legal limit, the areas will need to introduce more stringent requirements to control soot.

The EPA has previously determined that the areas covered in the legal notice have soot pollution at levels that cause significant health impacts.

“The Clean Air Act is clear about the steps the EPA needs to take to reduce dangerous soot pollution,” said Ryan Maher, an environmental health attorney at the Center for Biological Diversity. “Every day the EPA shirks its duties amplifies the harm to human health and wildlife.”

Soot pollution, also called fine particulate matter, has life-threatening consequences. It penetrates deep into the lungs, causing premature deaths, cardiovascular illnesses and respiratory diseases, including lung cancer and asthma. Even short-term exposure can aggravate lung disease and trigger asthma attacks.

“The 17 million people who live in these areas with unsafe levels of soot pollution deserve clean air and immediate federal action,” said Emily Reder, senior manager in the Center for Environmental Health’s illegal toxic threats program. “The EPA must face up to its responsibilities to protect these communities from the dangers of this pollution.”

Soot pollution, which results from a variety of sources, including the burning of fossil fuels and fracking, also harms the environment in several ways. Soot particles can travel long distances and settle on the ground or in water, damaging forests and commercial crops, contributing to acid rain and depleting nutrients in soil. Soot can also impair solar panels.

The formal notice submitted today is part of the two groups’ ongoing work to compel the EPA to protect human health and the environment from soot pollution in accordance with the requirements of the Clean Air Act. For more information about the fight against air pollution, please visit Protecting Air Quality Under the Clean Air Act.