The Environmental Protection Agency proposed a new rule Thursday that is expected to reduce cancer-causing pollution from chemical plants by 96 percent.

EPA administrator Michael Regan made the announcement in St. John the Baptist Parish, an area of Louisiana saturated with dozens of petrochemical plants and refineries. The proposal, which is being reviewed, aims to significantly reduce emissions of toxic and other harmful air pollution from chemical plants, including the highly toxic chemicals ethylene oxide (EtO) and chloroprene.

If successful, the rule will pull approximately 6,000 tons of pollution out of the air.

“I pledged to prioritize and protect the health and safety of this community and so many others that live in the shadows of chemical plants,” Regan said Wednesday. “I’m proud that this proposal would help deliver on that commitment.”

The proposal marks the beginning of a new era of environmental enforcement in the Cancer Alley region. Previous White House administrations and state officials had largely ignored decades of pleas from residents to do something about the pollution and high cancer rates.

St. John the Baptist Parish is west of New Orleans on the edge of the Mississippi River and forms part of what environmental activists call “Cancer Alley.” Cancer rates in the area are higher than in the rest of the country, according to Louisiana State University’s interactive cancer maps.

Although the area is 55 percent white and 40 percent Black, many of the 150 petrochemical plants and refineries are primarily located in neighborhoods of color. Earlier this year, the Department of Justice filed a lawsuit against two companies over a plant located in the area, alleging they have violated the Clean Air Act and “present an imminent and substantial endangerment to public health and welfare.”

Last week, several Black women-led environmental groups filed a federal lawsuit against the leaders of neighboring St. James Parish, alleging environmental racism.

Dionne Delli-Gatti, an associate vice president at the nonprofit Environmental Defense Fund, said in a press release that the new proposal was a “vital measure” in efforts to reduce “toxic petrochemical pollution” and to protect the people who have “borne the brunt of the health threats.”

She added: “Toxic air pollution from petrochemical facilities has been poisoning communities, especially the many low-income areas and communities of color that live in the shadow of these facilities.”