In Louisiana’s petrochemical belt, some of the people most exposed to toxic air have the least information about what they are breathing. A new investigation by the nonprofit newsroom Floodlight, produced in partnership with The Guardian and with contributions from the Louisiana Illuminator, finds that the state’s public air monitors are frequently located miles from major industrial polluters and fail to test for some of the most dangerous chemicals released along the corridor between Baton Rouge and New Orleans.
That stretch of roughly 85 miles, widely known as “Cancer Alley,” is home to dozens of refineries and chemical plants and to many predominantly Black communities. According to the reporting, cancer rates from toxic air pollution there are among the highest in the country, yet residents living near heavy industry often have no reliable way to learn what is in the air around their homes.
What the analysis found
Floodlight identified Louisiana’s top 25 industrial air polluters using emissions companies self-report to the U.S. Environmental Protection Agency, then measured each plant’s distance to the nearest public monitor and checked which pollutants those monitors actually track. As reported by Verite News, ten of the state’s heaviest air-polluting facilities operate without a single public air monitor within five miles.
The gaps extend to specific chemicals. Dow Chemical’s plastics factory in Plaquemine, one of Louisiana’s biggest air polluters, releases pollutants including ethylene oxide, a known carcinogen, but the nearest monitoring station is about eight miles away and measures only ozone. No public monitors track ammonia, even though CF Industries’ Donaldsonville plant reported emitting more than 7 million pounds of it in 2024. And the three chemicals researchers concluded account for the large majority of the area’s cancer risk, ethylene oxide, chloroprene and formaldehyde, are not monitored by the state at all.
The chemical findings echo peer-reviewed science. In 2023, atmospheric scientist Peter DeCarlo and other Johns Hopkins University researchers drove a mobile laboratory through the corridor. In 14 of the 15 locations they studied, cancer risks from toxic emissions exceeded EPA figures, in some places by up to 11 times, according to their work later published in the Proceedings of the National Academy of Sciences. “If large emissions from these facilities are happening far away from the air monitors, they’re often going to go unnoticed,” DeCarlo told Floodlight. “But that doesn’t mean they’re not gonna have an effect on the people who live there.”
A system that misses emergencies
The limits of the network were on display during a fire at Marathon’s Garyville refinery in August 2023. After a naphtha leak was reported to the Coast Guard in the evening, more than six hours passed before the Louisiana Department of Environmental Quality began monitoring the air, according to the reporting. The leak ignited the next morning, two nearby schools opened anyway, and residents within two miles were not ordered to evacuate until more than 15 hours after the leak began. A Guardian investigation found at least 29 residents were later treated at area hospitals.
The nearest state monitor measured ozone, not the volatile organic compounds released in the fire, and the plant’s own fenceline monitoring tracked a single chemical, benzene. By contrast, Marathon’s Los Angeles refinery continuously monitors more than 15 pollutants, as California rules require. Wilma Subra, a MacArthur-honored environmental chemist who examined the fire’s emissions, said the state’s network is “not adequate to protect the health of the community living in close proximity to these industrial facilities.”
Adrienne Katner, a Louisiana State University associate professor and former state environmental health scientist, concluded in 2022 that roughly 400 high-emission facilities in Louisiana had no public air monitoring, calling the situation “a public health emergency waiting to occur.” She argues the data gap protects polluters: “The theme is, if you don’t look for it, you won’t find it.”
Fewer monitors, less money
Even as advocates pushed for more coverage, the state moved the other way. Since 2020, Louisiana has lost four air monitoring stations, and spending by the LDEQ division that oversees air monitoring fell nearly 15% between 2020 and 2026, a drop of more than one-third when adjusted for inflation, according to the investigation. The agency operates 35 permanent stations and describes its network as “robust,” but acknowledges it is not designed to monitor pollution in fenceline communities and that “financial and technical constraints limit full monitoring coverage” of toxic pollutants.
Some reductions were deliberate. In 2022, regulators shut down a temporary monitor in New Orleans’ Irish Channel that had recorded elevated particulate matter, even after the EPA later urged the state to make it permanent. Louisiana’s 2022 monitoring plan included a section on “Environmental Justice Considerations” describing monitors in communities such as St. Rose and the Irish Channel; a year later, both the section and the St. Rose monitor were gone. When the EPA pressed the state on environmental justice, LDEQ replied that such considerations were “beyond the scope” of the plan.
Industry’s role in the legislature
For years, former state Sen. Cleo Fields, a Democrat now serving in Congress, filed bills to require major polluters to monitor emissions at their property lines and report the results. Each attempt died. “I got so frustrated because every year this was opposed by industry for no good reason,” Fields told Floodlight, adding that regulators “were working totally in concert with industry.” A more recent effort this year by state Sen. Royce Duplessis also failed.
The Louisiana Chemistry Association, a trade group representing 70 companies operating more than 100 sites statewide, has repeatedly helped defeat such measures. It found an ally in Republican state Sen. Eddie Lambert, who chairs the Senate environmental committee that killed the bills and who has received more than $28,000 in contributions from petrochemical, oil and gas and other polluting industries since 2020. Lambert said neither those donations nor his oil investments influenced his votes: “I don’t take that into consideration at all.”
In 2024, Lambert sponsored the Community Air Monitoring Reliability Act, which bars the use of air pollution data for enforcement unless it comes from EPA-approved monitors, equipment that can cost tens of thousands of dollars, far beyond the means of most community groups. An attorney for the chemistry association acknowledged at a 2024 committee hearing that the group helped draft the bill. A top EPA regional administrator at the time called the measure “inconsistent with federal law,” but the legislature passed it anyway. Association president David Cresson has defended the law, saying it ensures data used for enforcement meets minimum EPA standards and does not stop residents from monitoring for their own information.
The effect on the ground was immediate for Kimbrelle Kyereh, who lives a few hundred feet from chemical storage tanks in St. Rose and began collecting air samples in her yard in 2023. After the law passed, she stopped. “I shut my mouth like they wanted me to,” she said. The strategy has spread: after Louisiana acted, lawmakers in Kentucky, Ohio and West Virginia introduced similar bills using industry arguments, and the measures passed in Kentucky and Ohio.
Why the numbers matter
Lambert questioned the need for more public monitors, noting that plants already collect emissions data. “If we already get the information from the plants, why would we want to spend our resources there?” he asked. But under EPA rules, some facilities may report estimates rather than direct measurements, and those estimates can be far off. A 2025 ProPublica investigation found that when the EPA required temporary physical monitors, 97% of the comparisons showed facilities underreporting emissions; at Dow’s Plaquemine facility, measured vinyl chloride was more than 150 times higher than the company’s estimate.
For residents, the uncertainty is a daily fact of life. Tish Taylor lives less than a mile from the Denka Performance Elastomer plant in St. John the Baptist Parish, which suspended neoprene production in 2025 after federal regulators found its chloroprene emissions posed an “unacceptably high” cancer risk. The two closest public monitors, each about five miles away, measure only lead and ozone. When the wind carries something toxic through her garden, Taylor said, all she can do is guess: “I just have to wonder how much.”
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