A hard-won rule to cut chemical plant pollution is being unraveled — In April 2024, Tish Taylor and her father, Robert, stood behind President Joe Biden’s Environmental Protection Agency chief, Michael Regan, as he signed a regulation designed to dramatically reduce toxic pollution from petrochemical plants like those that cluster near the Taylors’ homes along the lower Mississippi River, in Louisiana. 
Taylor struggled not to cry through the signing ceremony, which followed years of demands from communities like hers — in the 85-mile corridor between New Orleans and Baton Rouge that has become known as Cancer Alley — for tighter limits on plants’ emissions. The new regulation, known as the HON rule, was “a wonderful gift to generations ahead of us,” Taylor said. “It’s hard for me to find the words to say how validated we felt.” 
For decades, regulations on emissions of hazardous chemicals such as toluene, ethylene oxide, and vinyl chloride have been weaker than restrictions on more common pollutants, such as those emitted by vehicles. 
The Biden administration took major steps to strengthen Clean Air Act rules on those hazardous air pollutants, and the HON rule was a centerpiece of that effort. Toughening requirements on six different pollutants at more than 200 petrochemical plants, it was one of a slate of regulations the Biden administration enacted on air toxics, each covering a specific industry, from steelmaking to tire manufacturing.
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But shortly after President Donald Trump began his second term, his administration began unraveling those rules, including the one the Taylors had so recently celebrated. Last year, Trump granted two-year exemptions from the HON rule to more than 50 petrochemical facilities. This July, he issued 20 more temporary exemptions, and the EPA said it would propose a rewrite of the regulation this fall. The new version is all but certain to significantly scale back the rule’s protections. 
“Everything that the Biden administration did to help protect us was pretty much just thrown in the garbage,” Tish Taylor said in July, and replaced by “a death sentence.” St. John the Baptist Parish, where her family lives, has the country’s highest risk of cancer from air pollution — nearly 50 times the national average. A disproportionate percentage of those exposed to the highest levels of pollution in the region are Black.
A set of amendments to several existing regulations on toxic air pollutants, the HON rule — which stands for Hazardous Organic National Emission Standards for Hazardous Air Pollutants — requires petrochemical plants to upgrade their pollution control equipment to reduce emissions of two hazardous chemicals: ethylene oxide and chloroprene. It also mandates air monitors at plants’ fencelines to measure concentrations of those chemicals and four more — benzene, ethylene dichloride, vinyl chloride, and 1,3-butadiene — and requires operators to carry out necessary repairs if emissions exceed limits. 
Tracey Woodruff, a Stanford University epidemiology and population health professor who formerly worked on toxic assessments at the EPA, said the pollutants covered by the HON rule are “the classic bad guys of toxic chemicals,” compounds that raise risks for breast cancer, liver cancer, leukemia, lymphoma, and reproductive problems. “We’ve known about their toxicity for decades,” she said, and “they should have been more highly regulated a long time ago.” 
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The HON rule also closed a long-standing loophole that freed plants from emissions requirements when they were shutting down and starting up — for example when carrying out maintenance, or ahead of a storm. With climate change fueling more extreme weather, that loophole has “a massive impact on what is actually getting released,” said Shiv Srivastava, policy director at Fenceline Watch, a Houston environmental justice group.
The HON rule was one of nine new air toxics rules issued by the Biden administration. The eight other rules targeted emissions from sectors including iron- and steelmaking, copper smelting, tire manufacturing, and coal-fired power plants. All nine have been or are now being rescinded, revised, or reconsidered.  
The HON rule was among the most wide-reaching of those hazardous pollutant regulations. “This is a big rule,” said Joe Goffman, who headed the EPA’s air office under Biden. Because air toxics rules typically address very specific types of industrial facilities, an individual regulation sometimes applies to only a handful of plants in a few locations, with pollution reductions often measured in just hundreds of pounds, he said. But the HON rule covered approximately 220 large petrochemical plants, so its footprint promised to be both bigger and more wide-reaching geographically. Nearly 60 percent of the facilities it covered are in Texas and Louisiana, home to the nation’s largest petrochemical production zones. The rest are scattered across the country, in states including Tennessee, Kentucky, West Virginia, Ohio, Illinois, and Alabama. 
The EPA estimated when the rule was finalized that it would prevent 6,200 tons of toxic air pollution annually, and slash emissions of ethylene oxide and chloroprene from the plants it regulates by almost 80 percent. In communities near HON plants, the agency said the regulation would reduce the risk of cancers related to air toxics by 96 percent. Facilities affected by the rule produce ingredients for common products such as plastics, paints, antifreeze, and cleaning and personal care items like detergent and shampoo. 
Weeks into Trump’s second term, the EPA invited companies to email the agency with requests for exemptions from the HON rule and Biden’s other hazardous pollutant regulations. In granting the postponements, Trump invoked a Clean Air Act provision that environmental lawyers say has never been used: allowing temporary exemptions to emissions rules if they are “in the country’s national security interests” and if the technology required to comply with a regulation is unavailable.