Asbestos Exposure in Sheet Metal Workers

If you spent your career fabricating and hanging ductwork, or if someone in your family did, and a diagnosis of mesothelioma, lung cancer or asbestosis has now come in, this page is for you. Sheet metal work does not sound like asbestos work. But for decades the ducts you built were joined with woven asbestos connectors, sealed with compounds that could contain asbestos, and hung in buildings and ships where other trades were spraying and wrapping asbestos all around you.

Sheet metal workers are one of the most closely studied groups of asbestos-exposed workers in the country, and the studies found asbestos disease again and again. In 1985 the sheet metal workers' union and the contractors' association set up a health trust to study the hazards of the trade, and it began screening members for asbestos disease in 1986. More than 26,000 sheet metal workers have been examined since then.

You do not need to remember brand names or have old paperwork. A work history is enough to start.

Why sheet metal workers breathed asbestos

Sheet metal workers built and installed the duct systems that move heated and cooled air through buildings and ships. For most of the 20th century, that work put them close to asbestos every day. Some of it was in the materials they handled. Much of it came from the trades working beside them.

Flexible duct connectors. Where ductwork met a fan, blower or air handler, sheet metal workers installed a short flexible connection to stop vibration and noise from traveling down the duct. For years that fabric was often woven asbestos. A 1939 article in the industry's trade journal said flexible connections were "often used to prevent transmission of vibrations thru metal duct systems," and named flexible woven asbestos for the job (Asbestos, Sept. 1939). A 1951 label for Grant Wilson's Flexi-Duct in our library describes it as asbestos woven duct material for stopping noise and vibration in ducts. A 1955 Grant Wilson sample envelope offered its Vibra-Stop connector in a Type A (asbestos) version, and a 1955 advertisement describes the asbestos, canvas or neoprene fabric. Workers cut this cloth to length, crimped or riveted it into metal strips, and tore out old connectors when systems were replaced. See Grant Wilson for more on the company, and our page on asbestos textiles.

Duct sealers and tapes. Seams and joints in ductwork were sealed with compounds and tapes. Some contained asbestos. A NIOSH list of trade-name products from its 1972–74 national survey, forwarded in a 1977 Celanese memo, lists a Chicago Mastic "Metal Duct Sealer" as containing 2% asbestos. Grant Wilson also sold Gum-Bestos, a pre-gummed asbestos paper tape.

Asbestos paper and asbestos ducts. The asbestos industry's own trade journal, Asbestos, described asbestos paper used on metal ducts in 1939, and in 1940 it featured Philip Carey's Careyduct for air conditioning and articles on duct insulation. See our page on asbestos paper and millboard.

Other trades' insulation and spray fireproofing. This was often the largest source. Sheet metal workers on new construction worked alongside insulators who were spraying asbestos fireproofing and wrapping pipes and ducts. Researchers who ran the national screening program wrote that sheet metal workers were exposed mainly while working beside insulators applying spray-on asbestos, a practice banned in 1973. Hanging duct meant drilling, cutting and fastening into ceilings and steel already coated with that material. See spray-applied fireproofing, our page on sprayed asbestos, and our page on bystander and proximity workers.

Renovation and repair. Exposure did not stop in 1973. Older buildings still held asbestos, and sheet metal workers kept cutting into it to reroute and replace ductwork. A 1983 study of renovation work in buildings with sprayed asbestos measured sheet metal workers, carpenters and electricians at average breathing-zone levels below 2 fibers per cubic centimeter but above 0.1, which is today's OSHA 8-hour limit.

Shipyards. Ship ventilation systems were built by sheet metal workers in the same tight compartments where insulators, pipefitters and boilermakers worked with asbestos. In the screening studies, shipyard work was one of the factors that predicted asbestos-related X-ray changes. See shipyards and maritime work and Navy veterans.

What the screening studies found

In 1985 the Sheet Metal Workers International Association and the Sheet Metal and Air Conditioning Contractors' National Association formed the Sheet Metal Occupational Health Institute Trust (SMOHIT) to look at the health hazards of the trade. Its asbestos screening program began examining members in 1986. Researchers have published a long series of studies from it and from earlier work in New York.

• About one in three long-time workers had X-ray changes. Among 9,605 U.S. sheet metal workers who had entered the trade at least 20 years earlier, 31.1% had asbestos-related changes on chest X-ray. Most were pleural changes, such as pleural plaques and thickening. Among those 40 or more years out from entering the trade, the figure was 41.5%. Smoking and shipyard work raised the odds. The researchers noted that only about half of eligible workers took part, which may have affected the overall rate.
• The researchers were struck that the workers did not use asbestos directly. An early report from the program found asbestos disease common among sheet metal workers "although they do not use asbestos directly," and suggested that asbestos already in place in buildings may also be causing disease.
• More deaths from mesothelioma and asbestosis than expected. A study following 17,345 program participants with 20 or more years in the trade found significantly more deaths from mesothelioma, pleural cancers and asbestosis than expected from U.S. death rates. A later update through 2010 found the same excess for mesothelioma and asbestosis. Lung cancer deaths overall were about as expected, but lung cancer risk rose with the amount of scarring in the lung tissue on X-ray, even after accounting for smoking.
• New York findings came first. A proportional mortality study of 331 deaths among New York sheet metal workers found that lung cancer made up a much larger share of deaths than expected, and that six deaths were from mesothelioma.
• A mesothelioma study in Canada. In a British Columbia study of 51 mesothelioma cases, sheet metal work was among the occupations with the highest risk. The study was small, so the estimate is imprecise.
• Later entrants fared much better. A 2019 study of 26,397 workers found that those who entered the trade after U.S. asbestos rules took effect in the 1970s developed asbestos disease at much lower rates. That is good news for younger workers. It also shows that most of the disease came from the years before the rules, though workers who started later were not entirely spared.

Asbestos disease appears decades after exposure. This gap is called latency. A worker who started in the 1950s, 60s or early 70s may only now be diagnosed.

Where the trades overlap

Many sheet metal workers also did service work, and many worked shoulder to shoulder with other trades. If that sounds like your career, these pages may also help:

• HVAC and appliance workers, for furnace, boiler and duct service work
• Insulators, the trade whose materials most often filled the air on job sites
• Pipefitters and plumbers and welders
• Carpenters and construction workers and construction
• Utilities and power plants and petrochemical refineries

The diseases that matter here

Asbestos exposure is linked to several diseases. Each has its own medical and legal questions.

• Mesothelioma. A cancer of the lining of the lungs (pleural) or abdomen (peritoneal). Asbestos causes most cases. It is the disease most clearly tied to asbestos and the one trusts and courts treat most directly.
• Lung cancer. Smoking causes most lung cancer. Asbestos also causes it, and the two together raise the risk far more than either alone. A smoker can still have an asbestos lung cancer claim.
• Asbestosis. Scarring of the lung tissue from heavy or long exposure.
• Pleural plaques and thickening. Changes in the lining of the lungs. These were the most common findings in the sheet metal screening program.
• Other cancers, such as cancers of the throat, stomach and colon, where the evidence is weaker but some trusts still pay.

If you worked in the trade before the late 1970s and have not been checked, our free screening is a chest X-ray read by a B-reader, with a CT scan if needed. It looks for asbestos-related changes. It is not a test for mesothelioma.

Family members were exposed too

Dust rode home on work clothes, in hair and in the car. Spouses who shook out and washed those clothes, and children who greeted a parent at the door, could breathe it. This is called take-home exposure. Some family members have developed mesothelioma decades later. If that is your situation, see our page on take-home exposure.

Claims for sheet metal workers and their families

If you or a family member worked in the trade and now has an asbestos disease, you may have more than one way to recover compensation. These paths can run at the same time.

Asbestos bankruptcy trusts. Many companies that made asbestos products went through bankruptcy and set up bankruptcy trusts to pay people they harmed. Each trust has its own trust distribution procedures and pays a set share of each claim's value, called the payment percentage.

• Duro Dyne. Duro Dyne, a maker of flexible duct connectors, reorganized in bankruptcy in New Jersey and set up the Duro Dyne Asbestos Personal Injury Trust. Its rules say flexible duct connectors are the only asbestos product the trust believes it is responsible for. They list sheet metal workers, sheet metal mechanics and apprentices, duct installers, and HVAC and furnace installers as qualifying occupations. A claimant must show direct work with Duro Dyne asbestos connectors.
• Insulation, spray fireproofing and other makers. Because so much of a sheet metal worker's exposure came from other trades' materials, claims often also run against the trusts of insulation, spray-fireproofing and other product makers whose materials were on the same job sites.

Learn more on our trust claims page and in understanding asbestos trust claims.

Lawsuits. Companies that are still in business can be sued directly, including product makers and, in some cases, the owners of the sites where you worked. Whether a lawsuit makes sense depends on your work history, your diagnosis and your state's law. See understanding mesothelioma lawsuits.

Deadlines. Every state sets a time limit, called a statute of limitations, that usually runs from diagnosis or death. Some are short. Calling soon after a diagnosis protects your options.

We cannot promise any result. What we can do is listen to your work history, explain which claims may fit, and do the work of tracing products and filing claims. There is no fee unless we recover compensation for your family.