Updated Dec. 8, 10:40 p.m. ET

When LaTunja Caster started working at the Olin Corp. chemical plant outside of McIntosh, Alabama, she had no idea that asbestos was used in the production process. But when she became a union safety representative around 2007, she started to pay attention.

In certain parts of the plant, "you would see it all the time," she said. "You definitely breathed it in."

Six other people who worked in the plant, some with experiences as recent as this year, echoed her recollections about exposure to the potent mineral that has long been known to cause deadly cancers like mesothelioma and a chronic lung condition called asbestosis that can make it difficult to breathe.

Though designated asbestos workers were given protective gear and had special training, electricians, millwrights and general maintenance staff got no comparable protection even though they, too, were exposed, they told ProPublica. The same was true of some contract workers.

Carrie Jenkins, a longtime contract janitor, said she scraped dry asbestos off the locker room floor and threw away workers' protective suits, which were sometimes caked with the substance. She said she was offered no protective gear herself, and worked around asbestos even when she was pregnant. "They never told us how dangerous it was," she said.

Andy Lang, a contract pipe fitter, worked in the asbestos-ridden part of the plant without protective gear on and off from the late 1990s to 2019, he said. Asbestos would go "flying" and land everywhere; anyone who spent time there would have breathed it in, he said, including him. "Ain't no doubt in my mind," he told ProPublica.

Though he has not experienced lung problems, his sister did. A plant employee who worked a variety of jobs, Bertha Reed spent time in areas where workers handled asbestos, Lang said, retiring as a lab analyst.

She was diagnosed with lung cancer and died in 2017 at 64. An avid hunter and fisherwoman who loved to travel and shop, she left behind a husband, two children and several grandchildren and great-grandchildren. Reed never smoked cigarettes, her brother said. He blames the chemicals she was exposed to at the plant. "There was nothing safe about it," he said.

For decades, workers were largely silent about the dangers they faced in asbestos-dependent chlorine plants like the one near McIntosh. But in the weeks since ProPublica revealed unsafe practices at a plant in Niagara Falls, New York, people who worked at other chlorine plants across the United States have voiced concerns about the way asbestos was handled at their facilities. One former engineer at a plant outside Las Vegas said the substance was difficult to control. Former lab analysts at a Texas plant said colleagues there raised issues about potential exposures with safety managers in 2018.

The workers are speaking up as the country's two main chlorine producers, Olin and OxyChem, battle to continue using asbestos at their plants, despite proposed bans on the substance put forward by the Environmental Protection Agency and members of Congress. The workers' accounts undermine the companies' long-standing contention that the substance is used safely and that workers are seldom exposed.

Olin did not return calls or emails from ProPublica. While CEO Scott Sutton told shareholders that the McIntosh plant recently stopped using asbestos, two of its other plants still use it, federal records show. OxyChem, which runs five asbestos-reliant plants, told ProPublica that it prioritizes worker safety and that its facilities are "operated under high standards and strict regulatory controls." It did not respond to specific concerns that former workers raised about its plants.

But Rep. Suzanne Bonamici, a Democrat from Oregon, said it was "deeply troubling that workers from multiple chlor-alkali facilities are now coming forward with stories of dangerous exposure to asbestos at their workplaces."

Said U.S. Sen. Jeff Merkley, an Oregon Democrat: "It's more clear than ever [that] we can't just trust industry to self-regulate itself with something as dangerous as asbestos. While it breaks my heart to hear of more workers in more plants that lack adequate safety precautions, it adds momentum to our mission to ban all forms of asbestos."

Pressure washing asbestos off screens

Asbestos is a naturally occurring mineral that was once used widely in construction and industrial operations. In recent years, dozens of countries have deemed the mineral so dangerous that they've banned its use entirely. The United States doesn't allow asbestos mining, but it has no prohibition on importing asbestos. Olin and OxyChem are among the few companies that buy it from other countries and use it in domestic plants.

The material is a key part of the production process in the nation's oldest chlorine plants; it serves as a protective coating on large metal screens that sit inside tanks of corrosive chemicals. When a screen needs to be re-coated, workers pressure-wash the old asbestos off, then dip the screen into an asbestos slurry. They bake the new asbestos onto the screen before returning it to service.

In interviews, more than two dozen people who worked at asbestos-dependent plants across the country described the process as dirty and outdated. (Both Olin and OxyChem have newer plants that make chlorine without asbestos, but the companies have resisted updating all of their facilities, saying the upgrades are cost prohibitive and would not significantly improve worker health.)

Olin opened its plant near McIntosh, a small town about 40 miles north of Mobile, in the 1950s. The ground there is rich in salt, a key ingredient in chlorine manufacturing. The plant's early production process involved mercury, a toxic metal that went on to contaminate the groundwater, EPA records show. It started using asbestos in 1978.

The plant has a complicated relationship with the residents of McIntosh, many of whom are Black or Native American and whose families have lived there for generations. At least three times in the past three years, the plant has released chlorine into the atmosphere, government records show. Scores of residents are now suing Olin, alleging in court documents that the plant failed to warn them about the leaks and they suffered as a result. The company denies those claims, and the case is ongoing.

Still, Olin is a major employer in McIntosh and supports the local schools and community improvement association. The corporation's name and logo loom large around town, adorning even the local walking trail. Many residents are reluctant to criticize the company publicly.

Inside the plant, workers struggled to keep the asbestos contained, according to the seven people who worked there. They were told they could stay safe by keeping the material wet, preventing it from becoming airborne. But that was an impossible task, several of them told ProPublica.

A slight breeze would cause the asbestos to dry, said Chris Murphy, a former union president who worked in the maintenance department from 2009 until 2020. It wasn't unusual to find it settled on machines and caked onto the beams overhead, he said. "Any areas that didn't stay wet," he said, "you'd find it."

Asbestos was just one of many hazards at the plant; more immediately concerning was a possible explosion or hazardous gas leak. Still, the plant's safety managers discussed it regularly and scrubbed the asbestos area in preparation for regulator inspections, said Caster, the former union safety representative who worked at the plant until 2020.

For years, plant officials knew when to expect the Occupational Safety and Health Administration. In 2001, the plant won admission into OSHA's Star Program, which exempts facilities that commit to high safety standards from random, unannounced inspections. Instead, OSHA makes re-evaluation visits every three to five years. The McIntosh plant withdrew from the program in 2015, several months after a chlorine release sent an employee to the hospital and OSHA fined the company $8,500, government records show.

In a statement provided after this story was published, OSHA said it had inspected the plant seven times after its withdrawal from the program, mostly on account of chlorine exposures, and that its records did not indicate any problems with asbestos hazards.

"Although the procedures for on-site evaluations are designed to reveal possible safety and health management failures, OSHA cannot rule out breaches in health and safety management when we're not onsite," an agency spokesperson said.

Tracking asbestos into the lab on their boots

At OxyChem's chlorine plant outside of Corpus Christi, Texas, workers in the lab started asking questions of their own in 2018, multiple former employees told ProPublica. Among their other duties, the lab workers analyzed asbestos samples delivered to them by workers who handled the material. The lab employees feared the asbestos workers were inadvertently carrying the substance into the lab on their boots and protective suits, which they often wore around their waists.

People in the lab also worried that, once dry, tiny fibers from the samples could escape into the air. The lab employees did not have protective breathing devices known as respirators.

When one of them raised concerns, the plant's safety managers sampled the air quality and deemed it safe, the former employees said. But the results did little to convince some employees that there was no exposure risk.

Teresa Hunt was in charge of the asbestos training program and air-quality sampling at OxyChem's plant in Tacoma, Washington, from the 1990s until 2001 — just before it stopped making chlorine in 2002. (From 1997 to 2002, the facility was owned by Pioneer Companies, news clips show.) The plant tried to control the asbestos with special fans, Hunt said, but they weren't enough. "Most people of course they were exposed to it," she said. "The stuff was all around us."

The plant offered top-of-the-line respirators to workers, Hunt said, but few employees took the threat of asbestos exposure seriously. "As a teacher, I had trouble getting them to listen to me," she said, echoing the reality that the other threats at the plant felt more imminent.

Hunt said she has not seen a high incidence of cancers among former plant workers, many of whom are still in close contact. Lately, though, she has been trying to get her insurance to cover a lung X-ray to look for signs of asbestos-related damage. "My God, I worry about it," she said.

Controlling the asbestos was also a challenge at Olin's plant in Henderson, Nevada, said Dawn Henry, the plant's engineer from 2004 through 2010. Although the asbestos workers at the facility outside Las Vegas wore personal protective equipment during the most dangerous tasks and supervisors tried to enforce the safety standards, "you can only do so much," she said. "It is a messy job."

In the desert heat, Henry said, it was impossible to expect all the asbestos would stay wet. "It wasn't like it was in a clean room," she added. "It was in a room that was open to the atmosphere. The building was adjacent to the offices where the engineers worked. It was a one-minute walk away. The garage door was always open."

Olin, which acquired the Henderson plant from Pioneer in 2007, announced plans to stop making chlorine there in 2016. The facility now produces bleach and hydrochloric acid, according to the company's website.

The accounts from workers stand in sharp contrast to what Olin and OxyChem have put on the record about worker safety in their plants. For decades, they've said their workers are rarely exposed to asbestos. The argument has been key to their success in beating back previous bans proposed by the EPA and Congress.

"Everyone makes the argument that this is a problem of the past, we do things better now," said Columbia University historian David Rosner, who researches the harm done by industrial pollution. "This has been the historical argument, the legal argument and the way of putting off the inevitable, which is the need to ban this stuff."

The EPA recently used the companies' own exposure-monitoring data to help determine that workers at chlorine plants — including those who don't handle asbestos — were at an unreasonable risk of being hurt by it, using the finding as the basis for the agency's latest proposed ban.

Breathing troubles in a retired worker

And in October, ProPublica examined the conditions at the OxyChem plant in Niagara Falls. Former workers there said asbestos stuck to the ceiling and walls, contaminated their break room and drifted out of open doors and windows before the plant closed late last year.

After the story was published in collaboration with NPR, other former employees at the Niagara Falls plant said they, too, had been exposed to asbestos. Ronald Hulsizer Sr. repaired pumps and instruments in the building where the material was handled. There was asbestos dust everywhere, he said, adding that it sometimes blew into an adjacent building.

John Mountain said he worked around asbestos until he retired from the Niagara Falls plant in 2013. He now has trouble breathing, he said. His doctors have told him his lungs are seriously damaged. Mountain used to smoke cigarettes; people who work around asbestos and smoke face a much higher risk of asbestos-related disease than those who don't.

But he didn't know that when he was a young man. In fact, his bosses told him the opposite, he said. "They used to tell us if you smoked, the asbestos didn't bother us as bad," he said.

Mountain said he was recently back at the plant, doing contract work to help decommission it. There's still a lot of asbestos on the site, he told ProPublica. "They have to get rid of all of the cells," he said, referencing the large tanks where chlorine was made. "You can see [asbestos] on the outside of them."

In the month and a half since ProPublica's reporting was published, some advocates have called on the EPA to expedite its latest proposed ban, which will likely take several months to be finalized. Others have rallied behind an effort to pass a law banning asbestos, which would be more difficult for opponents to overturn in court than an EPA rule. Five House members have signed on to co-sponsor the bill in recent weeks.

It is unlikely that the bill will be considered during the current lame-duck session before the new Congress begins in January. But advocates plan to keep the pressure on, said Linda Reinstein, co-founder of the Asbestos Disease Awareness Organization. Her group recently sent a letter to the EPA that cited ProPublica's work and urged the agency to dig deeper into the companies' ongoing use of asbestos.

"The brave workers who shared their stories prove yet again that there is no safe or controlled use of asbestos," she told ProPublica. "The scourge of asbestos death and disease will be with us for decades to come unless Congress acts now to ban this chemical once and for all."

Photography by Rich-Joseph Facun.