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When a Dirty Workplace Is an Explosive Hazard

Combustible dust has killed or burned hundreds of American workers, but politics and bureaucracy have stalled efforts to clean it up.

| Tue May 29, 2012 5:00 AM EDT
Simulation of a metal dust flash fire inside the Hoeganaes plant in March 2011 that injured one worker.

Small fires were a part of the job at the Hoeganaes Corporation metal powder plant in Gallatin, 30 miles northeast of Nashville. By early 2011, some workers later told investigators, they had become practiced in beating down the flames with gloved hands or a fire extinguisher.

The company's own product—a fine iron powder sold to makers of car parts—fueled the fires. Sometimes, powder leaked from equipment and coated ledges and rafters. Under the right conditions, it smoldered. Wiley Sherburne, a 42-year-old plant electrician, sometimes told his wife how this dust piled up everywhere, she recalled. On quieter weekend shifts, he said he could hear the telltale popping sound of dust sparking when it touched live electricity.

In the early morning of January 31, 2011, Sherburne was called to check out a malfunctioning bucket elevator. Near his feet, electrical wires lay exposed. When the machine restarted, the jolt knocked dust into the air. A spark—likely from the exposed wires, investigators later concluded—turned the dust cloud into a ball of flame that engulfed Sherburne and a coworker.

"He's burned over 95 percent of his body," doctors told Sherburne's wife, Chris, when she arrived at the Vanderbilt University Medical Center's burn unit. "He's not going to live." Wiley died two days later.

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He wasn't the last Hoeganaes worker to perish in a dust fire. Another blaze struck in March, then a third in May. In all, five workers died in accidents that shook this small community. Each man left behind a wife and children. One had four children under 11. Another had become a grandfather the day before the explosion.

Each of the blazes involved combustible dust, a little-noticed danger that has killed or injured nearly 1,000 workers across the country during the past three decades. The fuel has varied—wood, nylon, coal, flour, plastic, sugar—but the effects have been similarly devastating. Since 1980, more than 450 accidents involving dust have killed nearly 130 workers and injured another 800-plus, according to a Center for Public Integrity analysis of data compiled by the federal Occupational Safety and Health Administration and the US Chemical Safety Board. Yet a push to issue a rule protecting workers from the danger has stalled in the face of bureaucratic hurdles, industry pushback, and political calculations.

imperial sugar explosion OSHAAftermath of a 2008 dust explosion that killed 14 people at an Imperial Sugar refinery in Georgia US Chemical Safety Board

OSHA, in a statement, said it must "make difficult decisions as to how to best allocate the agency's limited rulemaking resources." While addressing dangers like combustible dust and dangerous substances breathed by workers are important, the agency said, it "has placed a great deal of emphasis on broad rulemaking efforts that have the potential to result in fundamental changes safety and health in the workplace."

Representatives for Hoeganaes refused interview requests. In legal filings, the company has denied violating safety standards at the Tennessee plant where Wiley Sherburne died.


"All of a sudden one day—boom"

A dust fire is, in a sense, the result of a perfect storm. The powder has to form a cloud in a confined area and touch an ignition source, such as a spark, flame, or overheated pipe. Often, workers don't know that the dust lurking on flat surfaces could, when dispersed in a cloud, fuel a violent explosion. But experts, worker safety advocates and government officials have been sounding alarms for years.

"It goes along for years with the dust building up, building up, and everything's fine, nobody's harmed, nobody thinks anything about it," said Sandra Bennett, an official at the Tennessee Occupational Safety and Health Administration, which investigated the Hoeganaes accidents. "All of a sudden one day—boom."

"It goes along for years with the dust building up, building up, and everything's fine, nobody's harmed, nobody thinks anything about it. All of a sudden one day—boom."

Standards to address the danger have existed for more than 85 years, but following them is voluntary for many plants. Where they are mandatory, enforcement is so haphazard that the association that sets the standards believes this policing duty should be placed in OSHA's hands. The agency seems to agree. In 2009, OSHA announced it was starting to work on a rule to address combustible dust. But making new rules is a difficult process—costly for industry, politically tough for agencies—and three years later, the dust rule is still stuck in its early stages.

Top agency officials refused to discuss the rule's status. In a statement, OSHA said, "Prevention of worker injuries and fatalities from combustible dust remains a priority for the agency." But, the statement said, developing the rule is "very complex" and "could affect a wide variety of industries and workplace conditions. As a result it has been moved to long-term action to give the agency time to develop the analyses needed to support a cost-effective rule."

News of OSHA's decision to delay the rule reached Chris Sherburne at the end of January, around the first anniversary of her husband's death. "I just couldn't believe it," she said. "You put it on the back burner and that's where it's going to stay."

Her frustration is shared by victims' families who have seen other health and safety rules similarly stalled, shelved, or eviscerated. Whether it's combustible wood dust at a sawmill, disease-inducing beryllium at an aluminum smelter, or lung-wrecking silica at an iron foundry, OSHA standards allow some conditions that even the government's own scientists consider unsafe.

OSHA, in a statement, said it is "committed to protecting workers" but that "numerous steps in the regulatory process mean OSHA cannot issue standards as quickly as it would like."


metal dust OSHAFine metal dust collected at the Hoeganaes plant (penny shown for scale) US Chemical Safety Board

metal dust and motor OSHAMetal dust near exposed wiring on an elevator motor near the site of the fatal January 2011 explosion in the Hoeganaes plant  US Chemical Safety Board

"Close calls for something that could kill somebody"

Documented dust explosions have been killing workers since at least the late 1800s, and technical publications discussing the hazard date to the early 20th century.

The Chemical Safety Board (CSB), an independent federal agency, has examined a handful of major dust accidents and identified disturbing trends. The board, however, can't issue or enforce rules. And records show that the plants involved in the catastrophic accidents the board investigated also had a history of smaller dust fires.

"You have to consider all those fires as close calls for something that could kill somebody," the board's chairman, Rafael Moure-Eraso, said in an interview. "Hoeganaes is precisely the case in point."

At the Gallatin plant, periodic small dust fires ignited in certain areas. Employees told state inspectors they put out blazes more than once a month. Because the fires had done little damage, workers had come to accept them as part of the job, investigators found. That changed the January day a dust cloud ignited and fatally burned Sherburne and Wayne Corley.

Two months later, a worker accidentally knocked loose dust that had collected on a furnace and was engulfed in flames. He leaped off a ladder to safety and survived. Then, on May 27, sparks triggered an explosion of hydrogen gas leaking from a pipe. The blast shook dust loose from the rafters, and some of it ignited as it rained down on workers. "There was so much dust in the air that you could only see the areas where it was burning," one employee told investigators. Three workers died, and two more were injured. 

Hoeganaes was no stranger to deadly dust. The May accident in particular bore "striking similarities" to one that occurred in 1992 at the company's plant in Riverton, New Jersey, said the CSB's lead investigator, Johnnie Banks.

Richardson recalls burning dust covering him as he struggled to find an escape route: "I could hear it sizzling and cracking."

Twenty years later, Jeffrey Richardson remembers that accident well. A hydrogen explosion shook the building, and burning dust fell from the rafters. Richardson recalls it covering him as he struggled to find an escape route. "I could hear it sizzling and cracking," he said.

He was left with third-degree burns covering 97 percent of his body. He has one ear and one hand, though it has no fingers. His body is covered with skin grown in a lab; it heals slowly and tears easily. "They said my foot and my eyelids were the only place where I wasn't burned," he recalled recently. "I still to this day have a nurse come every day to dress wounds that I still have ongoing."

The company contested the 10 serious violations OSHA issued for that fire, and the agency cut the fine from $22,500 to $15,300. Hoeganaes is now contesting the 25 serious violations and $122,900 in fines assessed by Tennessee regulators after the 2011 accidents in Gallatin.

Optional standards, lax enforcement

Many plants already are required to follow rules addressing combustible dust—at least in theory.

The National Fire Protection Association (NFPA), a nonprofit group that sets an array of standards and conducts research and training, first issued guidance in the 1920s. Since then, committees of industry officials and experts have updated the association's combustible dust standards regularly. Many experts praise the standards, and OSHA often points to them as widely recognized practices when trying to issue violations.

But two problems limit the standards' reach: They are optional in many areas, and, where they apply, enforcement is often lax or nonexistent, experts have found.

Some state and local governments have adopted the NFPA standards as part of their fire codes, while others have chosen the International Fire Code, which has general guidance on combustible dust and references the NFPA codes without explicitly requiring companies to follow them. Even where the rules apply, those charged with enforcing them are typically state or local fire inspectors. Inspections of industrial plants are rare, the CSB has found, and inspectors are often ill equipped to recognize even glaring dust hazards. "The rank-and-file first line of code enforcement is totally ignorant of the problem," said John Cholin, an engineer who has investigated dust accidents for 30 years.

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