Breathe easier: Mitigating welding hazards with ventilation and exhaust
May 03, 2022
The welding process creates contaminants that can cause harm. So, how do you get rid of them? One of our industrial engineers looks at solutions.
I once visited a welding shop where I couldn’t see the far side of the building because the fumes created by the welding processes left a haze that hung around constantly. “It’s just smoke,” the client told me.
That may have been acceptable 50 years ago—hello, restaurant smoking sections—but today we know better. That smoke contains particulates, gases, and vapors. It contains visible and invisible airborne contaminants. And those contaminants can cause a lot of harm to employees, the process, the building, and even the product quality. So, how can you get rid of them? Let’s explore some solutions and discuss how to mitigate the hazards associated with welding.
Contaminants generated by welding can cause a lot of harm to employees, the process, the building, and even the product quality.
Know your local regulations
In general terms, welding is a process of joining solid metal pieces together by melting either the base metal or adding a filler metal to create a bond. It can be done with similar or dissimilar metals. And the composition of those metals determines what fumes are created in the welding process. Why does that matter? Substances—including gases, vapors, and fumes—that are hazardous to human health are regulated under various codes and standards.
Here in Ontario, the Occupational Health and Safety Act dictates the requirements that employers and employees have with regards to a safe and healthy workplace. Ontario Regulation 833 covers the Control of Exposure to Biological or Chemical Agents. It also references American Conference of Governmental Industrial Hygienists (ACGIH) publications. These documents define exposure limits for hazardous substances—how much of a substance a human can be exposed to during a defined workday before it becomes dangerous to their health.?
When it comes to welding, ventilation and exhaust is the most effective way to mitigate hazards caused by exposure.
Most steels will generate iron oxide as a fume, which has a defined exposure limit. Different metals create different fumes. Metal coatings can also create fumes, like zinc oxide, which is created by welding galvanized steels. Exposure to fumes can cause symptoms that are mild and include irritation of eyes, nose, and throat but can also cause dizziness and nausea. Longer-term exposure leads to more significant health impacts, including metal fume fever, lung damage, and certain cancers. Welding stainless steel is extremely dangerous, as it creates hexavalent chromium, a known carcinogen. Some welding shield gases are asphyxiants. Employers must protect their employees from these hazardous substances.?
A welding lab at a community college in Virginia, featuring welding exhaust equipment.
Bring in the engineering controls: Ventilation and exhaust
In the hierarchy of controls used to mitigate safety hazards and keep employees safe, elimination is best. But if you can’t eliminate or substitute the hazard, engineering controls are the next most effective method. They’re more effective than personal protective equipment.
When it comes to welding, ventilation and exhaust is the most effective way to mitigate hazards caused by exposure. We want to remove the hazards from the employees’ breathing zone before they can even breathe them in.
In the hierarchy of controls used to mitigate safety hazards and keep employees safe, elimination is best. But if you can’t eliminate or substitute the hazard, engineering controls are the next most effective method.
Explore the best ventilation system design for your situation
Ok, so you’re ready to install some ventilation. You can just throw open a door to the outside and set up a box fan, right? That might sound tempting—and I’ve seen it in real life—but no. Proper ventilation system design is highly dependent on several factors:
- What type of welding are you doing?
- What materials are you using?
- Are you welding continuously or spot welding?
- How often are you welding? Is it constant process or sporadic? Does it last for five minutes or four hours? Are you welding every day or maybe only once a month?
- How large are the items you’re welding? Is it a small component? Or are you welding large structural members?
- Are you welding in an open building? Or a small room? Or even a welding booth?
- Does your welding area need space to move parts around? Or is there a defined location?
- What ventilation is currently in place?
All these factors need to come together for engineers—like my colleagues and I—to design a specialized welding exhaust system that will fit your needs. We’d also want to consider timing and budget, as these will impact what design is best for you.
For welding in an automotive plant, ducted exhaust and enclosures and welding curtains may be ideal.
Work with engineers to design a solution
Do you have an open shop where you’re welding large parts that change every day? General dilution ventilation might work best for you. We might design something called a push-pull system, where we supply air from one side of the shop and exhaust from the other. Typically, this type of ventilation system would be operational whenever the shop is occupied. Controls could be as easy as scheduling regular operational hours.
Do you run a repair garage with a little welding booth in the corner? A welding exhaust arm might work well. It gives you a little bit of flexibility and won’t take up much space. Controls could be an on/off switch where the operator turns the exhaust system on when they are welding, and off when they are complete.
Or maybe you’re a manager of a weld shop in an automotive plant. Ducted exhaust and enclosures and welding curtains might be ideal. We might even be able to reuse some existing infrastructure like ductwork, exhaust fans, etc. The controls could be tied into the main plant BAS system and could control the exhaust system to operate during regular shifts.
Whatever your situation, engineers can design a solution. In the end, you and your staff will be able to breathe easier in every way.