After three decades of attempts, the Environmental Protection Agency has banned the only form of asbestos still in use — part of a family of toxic minerals linked to lung cancer and other illnesses that cause about 40,000 U.S. deaths each year, the agency says.

The EPA on Monday formally prohibited the import and use of chrysotile asbestos, the last type of asbestos that U.S. industries use. The ban comes 33 years after a federal judge blocked the agency’s initial attempt to ban the cancer-causing mineral. While the use of asbestos has declined since, it remains a significant health threat.

“Folks, it’s been a long road. But with today’s ban, EPA is finally slamming the door on a chemical so dangerous that it has been banned in more than 50 countries,” said EPA Administrator Michael Regan.

The agency’s ban targets chrysotile asbestos, also known as “white asbestos,” the only one of the six forms of the mineral still being used in the United States. Resistant to heat and fire, the mineral’s use in the United States is limited to a small number of products, including automotive parts, sheet gaskets and brake blocks for use in the oil industry. Chemical manufacturers have also defended its continued use in making chlorine, which is used in pharmaceuticals, pesticides and to purify drinking water.

Asbestos use peaked in the United States in the 1970s, when more than 800,000 tons were used annually in manufacturing. In recent years, fewer than 1,000 tons of asbestos fiber have been imported annually. About 70 countries have banned chrysotile asbestos — the United States was one of few industrialized nations that still allowed it. But efforts by asbestos-exporting countries to preserve the international market have kept the mineral in wide use in developing countries. Russia is the world’s biggest chrysotile producer. China and India are the biggest consumers.

Drexel University Professor Arthur Frank, an expert on the dangers of asbestos exposure, said that while the EPA’s new rule is a step forward, other countries have gone much further by completely banning imports of products containing all types of asbestos.

“No other country has this kind of partial ban,” he said. “You just can’t use the stuff, period. End of story. We’re taking kind of half measures.”

Michal Freedhoff, who heads chemical safety and pollution prevention for the EPA, called the ban historic, saying it is the first time the nation’s updated chemical safety law has been used to outlaw a dangerous substance. That law, the Toxic Substances Control Act, was so weakened by the federal court’s decision in 1991 allowing continued asbestos imports and use that “it was rendered almost powerless to protect the people who needed protecting the most,” Freedhoff said.

In 2016, America’s long delay in confronting asbestos prompted bipartisan concern among members of Congress, who voted to overhaul the law, giving the EPA sweeping new authority to protect people from toxins.

Yet years passed with little action. When the Trump administration came to power, it shrank the agency’s staff, leaving the chemical safety office too small, underfunded and demoralized to accomplish its mission.

Finally banning asbestos was at the top of Freedhoff’s to-do list when she became the agency’s top chemical regulator in 2021. As a congressional staffer, she had helped write the 2016 legislation. On a call with reporters Monday, she described the new rule as “a symbol of how the new law can and must be used to protect people.”

The trade group representing the chlorine industry, the American Chemistry Council, has staunchly opposed the administration’s proposed ban since it was announced two years ago on the grounds that chrysotile asbestos is still used by about a third of U.S. chlor-alkali plants that produce chlorine. The industry group warned that banning this form of asbestos would make it difficult for water utilities to buy chlorine, threatening the safety of the nation’s drinking water.

Freedhoff said that once the EPA decided some of those concerns were valid, it changed its original enforcement timeline. Instead of having two years to phase out the asbestos diaphragms used to make chlorine and sodium hydroxide, the eight American companies that still use this technology will have five years, or in some cases more, to switch to alternatives. Yet imports of new asbestos diaphragms will be prohibited immediately once the rule takes effect, 60 days after it appears in the Federal Register.

Imports of asbestos-containing brake blocks and aftermarket automotive brakes, which have exposed car mechanics to the deadly airborne fibers, will be phased out after six months. And asbestos gaskets will be banned after two years.

While the change in compliance dates was a concession to chlorine manufacturers, most of which have already transitioned away from asbestos-based technology, the chemical industry did not greet it with enthusiasm.

In a statement, Steve Risotto, the American Chemistry Council’s senior director of chemical protects and technology, said supply chain bottlenecks and contractor shortages meant the industry needed more time to comply. “ACC has consistently advocated that a 15-year transition period is needed to support an orderly transition and to avoid a significant disruption of chlorine and sodium hydroxide supplies,” he said.

Environmental and public health advocates praised the new rule and urged the Biden administration to go further by addressing the other types of asbestos, arguing that anything less than a full ban doesn’t protect public health.

“I don’t want to be a Debbie Downer, but we’re not done,” said Linda Reinstein, president of the Asbestos Disease Awareness Organization. In 2006, her husband died of mesothelioma, a cancer closely tied to asbestos exposure.

Wary of federal rules that can be overturned by courts or weakened by future administrations, Reinstein is advocating for legislation that would outlaw all asbestos fibers and all uses. She’s skeptical of the EPA’s claim that chrysotile asbestos is the only form in use in the United States today.

“If you haven’t done product testing, if you haven’t searched for asbestos in consumer products, then you don’t know if it’s not being used,” she said, adding that, over a decade ago, laboratory testing conducted at her group’s behest identified five products with different combinations of asbestos fibers, including a children’s toy.

Although the use of asbestos has declined, in large part because of liability fears, construction workers, firefighters, paramedics and others who spend time in old buildings are still being exposed. Once building materials containing asbestos are demolished or otherwise disturbed, the mineral’s fibers can stick to skin and clothing, ultimately finding their way into people’s lungs. There is even a name, “asbestosis,” for a chronic lung disease caused by inhaling asbestos.