OAKLAND, Calif.— Conservation and public-health groups filed formal notice today of their intent to sue the Environmental Protection Agency for failing to review and update the air-pollution limits that protect human health from harmful nitrogen pollution nationwide.

The EPA is required to review these limits every five years. But the agency has not reviewed the limits since 2018, and has not updated them since 2010, despite new scientific evidence showing greater harms from nitrogen pollution than previously known.

“The EPA’s ongoing failure to keep these life-saving limits up to date has left people across the country at greater risk of fatal heart and lung disease,” said Ryan Maher, an environmental health attorney at the Center for Biological Diversity. “When the EPA ignores the steps that are legally required by the Clean Air Act to protect public health, it leaves us no choice but to sue.”

Nitrogen pollution is linked to a range of health problems, including increased risk of lung and heart disease, diabetes, birth problems, cancer and even death. This pollution also leads to excess nitrates in drinking-water supplies and soils, causing toxic algal blooms and harm to plants and wildlife.

“The diverse health harms from this pollution include the worst possible consequences,” said Kaya Allan Sugerman, director of the Center for Environmental Health’s illegal toxic threats program. “It’s imperative that the EPA uphold its duty to protect the public’s health and not blind itself to the dangers posed by outdated air-pollution standards.”

Nitrogen oxides result from burning fossil fuels at sources like power plants and cars. This pollution can also transform into detrimental ozone, also known as smog, and soot pollution.

Since the EPA last reviewed the air-quality limits for nitrogen pollution in 2018, the research linking nitrogen oxides to adverse health impacts has only become stronger. Recent studies have suggested nitrogen pollution is linked to dementia, even when pollution levels are below EPA’s current limits; depression; and worse COVID outcomes.

Today's formal notice was submitted by the Center for Biological Diversity, the Center for Environmental Health and the Sierra Club. It is part of an ongoing effort to compel the EPA to protect human health and the environment from air pollution, including nitrogen pollution, in accordance with the requirements of the Clean Air Act.

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