You'll encounter welding in any environment where workers must apply heat and pressure to join materials together. Buildings, cars, airplanes, ships, and roller coasters are just a few of the things welders make possible. But do you know how welding processes work? Or what hazards welders are exposed to? Or how to protect welders from welding fumes, which the International Agency for Research on Cancer has classified as carcinogenic?

"There is almost no training for industrial hygienists when it comes to welding hazards or identifying welding processes," said Mike Harris, PhD, CIH, FAIHA. Harris, who recently retired as a field industrial hygienist, has a unique perspective on welding—he is also a former professional welder himself.

Bringing a Welder's Perspective to IH

Harris started his career welding aircraft in the '60s. He then worked as a welder for military and civilian applications before he obtained his PhD in geomorphology and entered IH in the '80s. In his new role, he found himself once again working with people who cut and welded steel during petrochemical facility turnarounds. His experience with welding helped him to relate with the people he was protecting. "When we come into somebody's workplace, and we say, 'Oh man, this stuff is bad for you. You got to use the smoke sucker. You got to wear a respirator,'" he said, referring to some of the controls employed in welding processes, "it's a lot easier if you've been in their shoes."

But Harris realized that many of his IH colleagues lacked his familiarity with welding processes and hazards. "I'm the only industrial hygienist that I have met that has been a professional welder," he noted.

Harris drew on his experience to create a course on confined space ventilation for welding activities for his colleagues in the petrochemical industry. Then, he cowrote a book, Field Guidelines for Temporary Ventilation of Confined Spaces With an Emphasis on Hotwork.

"And then a few years after that, I realized that book was not adequate," Harris said. "It wasn't telling people how to identify … health hazards and where they were coming from." The result of this reflection was another publication, Welding Health and Safety for OEHS Professionals.

Continued interest in welding controls, combined with Harris' awareness that his knowledge was relatively unique, motivated him to create a videorecorded course that would be available to a wider audience. The virtual professional development course, recorded in 2008, was recently redeveloped by AIHA's eLearning team. "Welding: A Case Study in Occupational Hygiene" became available this summer for anyone to complete online at their own pace.

Developments in Welding Hazards

One reason why Harris has continuously updated his resources is because understanding of welding hazards has changed significantly over the years. "A lot has happened since then," said Harris, reflecting on his 2008 course. "The things that have happened in the last 15 years include an emphasis on manganese and on hexavalent chromium. And in the last few years, welding fume has been identified as an IARC Group 1 carcinogen, which is ugly."

IARC's Group 1 designation denotes agents sufficiently proven to be carcinogenic to humans. Prior to the agency's 2018 reclassification, IARC had designated welding fumes as a Group 2B carcinogen, or possibly carcinogenic to humans, since 1989. IARC estimates that 11 million welders and 110 million additional workers worldwide experience welding-related exposures.

Welding fumes consist of fine, solid particles of metal and other substances. Because there are many different welding processes, workers' exposures to specific chemicals in welding fumes may vary. NIOSH states that manganese, a metal present in most welding fumes, may cause neurological and neurobehavioral health effects. OSHA lists hexavalent chromium as a carcinogen associated with welding in chromium metal. IARC classifies molybdenum trioxide, another chemical associated with welding, as a Group 2B carcinogen. However, according to Harris, iron oxide is likely to be the primary carcinogenic agent in welding fumes, since almost all welding is conducted in carbon steel. Harris published an article on the carcinogenic potential of iron oxide in the April 2019 issue of the Journal of Occupational and Environmental Hygiene.

In 2022, even more recently than IARC's evaluation, researchers identified the rare but potentially deadly disease welder's anthrax. Inhalation of welding fumes, including iron oxide, may make welders more susceptible to lung infections and pneumonia, the researchers found. Iron oxide may be found in the lungs years after exposure, where it may act as a growth nutrient for bacteria or impair immune response.

In addition to the many hazardous chemicals in welding fumes, ultraviolet radiation from welding may cause ocular melanoma. OSHA also identifies burns, eye damage, electric shocks, cuts, and crushed toes and fingers as among other hazards associated with welding.

"This course has evolved from 'These are the processes. This is how to recognize them,' to 'Oh, by the way, here's manganese. Oh yeah, here's where you look for hexavalent chromium. Oh yeah, welding is a carcinogen,'" Harris said. "That's because this change has happened over this 15- or 20-year period of time."

What to Expect from the Course

The updated course is "designed for people who know nothing about welding," according to Harris. If you're a new industrial hygienist, or if you've recently changed jobs, you may unexpectedly find yourself responsible for the health and safety of welders and other workers around them. "This course will help you identify welding processes, be able to anticipate the health hazards associated with the welding processes, and use techniques for controlling those health hazards," Harris said. Essentially, the course follows the anticipate, recognize, evaluate, control, and confirm framework.

As mentioned previously, different welding processes are associated with different hazards. But for the majority, Harris explained, "most of the fume comes from the consumable, or the filler material that you add to the weld when you're melting it down." The course teaches participants to anticipate hazards using information provided on safety data sheets for consumables and then to collect exposure data via air sampling. Health hazards associated with thermal cutting processes will also be covered.

The lack of occupational exposure limits presents another challenge to controlling exposures. "We have a carcinogen affecting over 100 million people, and we don't have an exposure limit," Harris said. He noted that OEHS professionals often more easily convince management to implement controls when they can prove that a hazard is present at levels that regulatory agencies have deemed unacceptable. "But if you come and say, 'We've got a carcinogen out there, and we don't really know what an acceptable exposure level is,' what do you do?" Harris asked.

His answer: control banding. Although this practice is sometimes controversial in the IH and OEHS fields, it guides OEHS professionals in assessing and managing hazards that lack OELs. Harris' course includes an overview of control banding.

Finally, Harris outlines the many unique considerations for effective welding controls. It's difficult to eliminate hazards in welding processes or substitute safer materials or methods for hazardous ones "because there are specifications that tell you what consumable you need to use when you're welding what base metals together," Harris explained. Regarding engineering controls, "ventilation for welding is very difficult," he said. "The reason for that is that if you expose molten metal to the atmosphere, ugly things happen. You get oxygen and nitrogen combined with the weld metal and making it porous and brittle, which is not what you want. And so every welding process has some way of excluding the atmosphere from that molten pool."

Welding fumes are dangerous for people to breathe, but good for welding processes, because they push air away from the molten metal to enable a clean weld. "But the problem with ventilation is, it tends to blow that shield away," Harris said. "So ventilation can be used, but only with great care and only in a few circumstances." The online course shows participants "exactly how to use that ventilation and how to use it correctly and provides data showing that yes, it does work if you use it right," he continued. The course also covers personal protective equipment, such as powered air-purifying respirators.

"Welding: A Case Study in Occupational Hygiene" draws from Harris' decades-long careers in welding and industrial hygiene to provide a learning experience accessible to all IH and OEHS professionals. If you're interested in taking the course or learning more, visit AIHA's website.