January 6th, 2020 | Posted in Welding
“Hot work,” such as welding and thermal cutting, performed on carbon or stainless steel, exposes workers to toxic and hazardous fumes. Last month, we spoke with Certified Industrial Hygienist (CIH) Mike Harris, PhD of Hamlin & Harris, Inc. about the dangers associated with manganese that welders face. We caught up with Harris again this month to learn about another major threat found in welding fumes: hexavalent chromium (CrVI). Read on to learn about the risks of hexavalent chromium overexposure and how, according to Harris’s experience and expertise, a source capture device helps protect welders and others in the shop.
Hexavalent chromium is the +6 oxidation state of elemental chromium atoms, meaning it has lost six electrons and is now an unstable ion. Losing six negatively-charged electrons leads to a +6 valency, hence hexa-valent. Steel is made up of carbon and iron, but small amounts of chromium are present in carbon and stainless steel due to metal recycling.
“Elemental chromium is a low health risk,” Harris explained. “But putting it through the violent environment of the electric arc welding process strips electrons and creates highly reactive hexavalent chromium ions. Many will find electrons and become trivalent and less toxic, but enough will stay hexavalent to pose an exposure concern.”
According to the International Agency for Research on Cancer (IARC), hexavalent chromium is a group 1 human carcinogen, or cancer-causing agent. While the main concern is an increased risk for lung cancer, overexposure can also lead to irritation of the throat, nose, lungs, skin, and more.
In addition to welding, grinding, or thermal cutting of steel, problematic exposures are known to occur when painting with chromate-containing paint as well as chrome-plating.
Hexavalent chromium’s general permissible exposure limit (PEL), enforced by the Occupational Safety and Health Administration (OSHA), is remarkably low at just 0.005 milligrams per cubic meter.
“If you weld on stainless steel using metal insert gas (MIG) or “stick”/shielded metal arc welding (SMAW) techniques for more than 10 minutes, you’re going to get overexposed,” Harris stated. “The limit is that low. If you face it on a daily basis, the enhanced risk for lung cancer and other health issues is there.”
During the welding process, hexavalent chromium escapes into the air and the fumes spread throughout the shop. With such a low PEL, everyone in the shop needs to be protected, not just the welder. Owners who do not take action to manage welding fumes both compromise worker safety and are at risk for significant liability should someone become sick.
Harris recommends several possible solutions for decreasing or eliminating the risks of hexavalent chromium exposure.
“On top of personal respirators for welders, I strongly recommend using a local exhaust ventilation system to protect against hexavalent chromium,” he said. “Being proactive about controlling a carcinogen in the workplace is just modern business management, and using an LEV reduces concentration for everybody in the shop as well as the welders.”
Air Quality Engineering, Inc. (AQE) has manufactured effective and reliable indoor air quality solutions since 1973. Using state-of-the art technology, we offer industrial air cleaners that provide efficient, reliable protection for a variety of welding applications.
“I’ve tested Air Quality Engineering’s source capture devices while welding stainless steel, and the results were very encouraging,” Harris said. “Overexposure to hexavalent chromium is likely in typical workplaces engaging in stick or MIG welding, and we tested at an even higher concentration. Correctly used, their air cleaner got it from 0.6 milligrams down to 0.002 milligrams. It’s that effective.”
At AQE, we’re committed to customer care and satisfaction before, during, and long after installation. Our team of experts will work with you and find the customized solution to match the challenges and goals of your business.
Contact us to learn more.