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Welding fume exposure

What is the potential risk?

The International Agency for Research on Cancer (IARC) now classifies welding fume and ultraviolet radiation from welding as carcinogenic to humans.

During welding work, metals are heated to fuse them together. This process releases fumes that contain hazardous metals and other chemicals.

Welders and others working nearby who inhale welding fumes may develop occupational diseases and illnesses. Potential adverse health effects include:

  • Lung cancer
  • Neurotoxicity
  • Metal fume fever
  • Chronic obstructive pulmonary disorder (COPD)

Without effective controls in place, airborne levels of welding fume components can often exceed exposure limits, which are set at levels that minimize adverse health effects. Elevated exposures have been associated with welding mild steel, as well as aluminium, stainless steel, and other alloys. Both indoor and outdoor welding may result in high exposures.

Which industries pose risk of exposure?

More than 300,000 Canadians may be exposed to welding fumes in their workplaces, according to CAREX Canada, a research organization devoted to reducing exposures to carcinogens and reducing the risk of cancer. Welding activities occur in almost all industry sectors, including the following:

  • Welding trade contractors (used in most industries)
  • Repair and maintenance of vehicles and machinery
  • Construction — residential or commercial; both new builds and renovations
  • Oil or gas well drilling or servicing
  • Metal product and other kinds of manufacturing

How can I reduce the risk in my workplace?

The first step to reducing the risk in your workplace is to identify the potential for exposure to welding fume during various work activities. Asking welders and other workers can help with this process. The amount of fume produced as well as the specific contaminants and their levels will depend on:

  • The welding process and duration
  • The size and orientation of the workpiece
  • Base metals and any coatings present
  • Wire, rods, and flux (consumables) as well as shielding gas
  • Work environment, including how confined/enclosed the area is and whether ventilation is used

Welding fume often contains “designated substances,” which are chemicals that can cause cancer, sensitization, or reproductive effects. For example, manganese, which is a component of mild steel and many consumables, is a reproductive toxin. Nickel and chromium (VI), which are found when welding stainless steel and other alloys, are carcinogens. Other designated substances associated with welding include beryllium, cadmium, cobalt, and lead; they may be present in base metals or coatings.

The Occupational Health and Safety Regulation requires employers to eliminate exposures to these designated substances or otherwise control workers’ exposure to them below harmful limits. You must implement an exposure control plan (ECP) to keep workers’ exposures as low as reasonably achievable (ALARA) below the exposure limits if there are potential exposures to welding fume in your workplace and it’s not practicable to eliminate or substitute welding with a less hazardous process.

When welding processes are required and cannot be eliminated or substituted, the best option for controlling workers’ exposures is to use engineering controls. For example, installing local exhaust ventilation (LEV) systems can minimize exposures provided they are used correctly. If these engineering controls don’t reduce exposures below harmful levels, you will need to ensure your workers wear the appropriate respirators.

There are control measures you can take to reduce worker exposures to welding fume:

  • When possible, use other methods for joining/fusing (bolts, fasteners) or cutting metals.
  • Select alloys or consumables that contain lower concentrations of the more hazardous metals (e.g., using welding rods with lower levels of manganese).
  • Choose a welding process (e.g., pulsed, submerged arc, or tungsten inert gas welding) that generates less welding fume.
  • Install LEV systems such as portable fume extractors, on-gun extractors, welding booths, or exhaust hoods. These systems must be maintained to ensure they remain effective. Mechanical “general” ventilation may reduce the level of welding fume in the work area overall but often does not do enough to control the exposure of welders and workers nearby.
  • If it’s not practicable to use LEV systems in your workplace, welders will likely need to wear properly fitted respirators that provide the appropriate level of protection. A worker wearing a respirator that requires an effective seal with the face must be clean shaven where the respirator seals with the face.
  • Provide training and supervision to ensure engineering controls, welding equipment, and personal protective equipment are used and maintained correctly.

Since the exposure limits for some common metals associated with welding (e.g., manganese, nickel, chromium (VI)) are extremely low, more than one type of control will likely be needed for some applications. Both local exhaust ventilation and respirators may be required for welding processes (air carbon arc gouging, flux core, stick/shielded metal arc) that generate high fume levels. When chromium (VI) or beryllium are present in the fume, multiple controls will often be required even for welding processes with lower fume levels. Welding in confined spaces requires assessment by a qualified person to determine the specific controls needed to address exposures to welding fume and gases.

Finally, you must inspect and assess your workplace regularly to ensure that your risk controls are effective. The ECP must be reviewed annually in consultation with the joint committee or worker health and safety representative.

The following sections of the Occupational Health and Safety Regulation are most relevant to this risk.

Where can I find more information?

Publication Date: Mar 2022 Asset type: Risk Advisory Reference: RA 2015-23