By Maureen Paraventi, Editor
Clothed in protective gear, surrounded by flying sparks, the welder wields a powerful energy source and generates heat up to 15000°F in order to fuse two materials together into a strong joint – called a weldment – that will be permanent once the parts cool. An economical and efficient process, welding is vital to the construction, manufacturing, aerospace, automotive, railroad and shipping industries, among others.
Many of the potential dangers of using the kinds of energy sources (electric arc, gas flame, laser, electron beam, friction or ultrasound) and extreme heat required in welding are obvious and straightforward: burns, electric shock, vision damage and exposure to ultraviolet radiation at unhealthy levels.
Another risk – arising from the inhalation of hazardous fumes and gases – is more complex, in that both the types of toxins and the range of potential health effects are many.
Metals And Gases Contribute To Fumes
Welding fumes, which are condensed into very fine particles when a metal is heated above its boiling point, are a mixture of metallic oxides, silicates and fluorides, as well as particles from the electrode and the material being welded. Both the metals being welded and the coatings or residue on those metals can contribute toxins to welding fumes.
Among the metals and gases that welding fumes can contain are: aluminum, antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, silver, tin, titanium, vanadium, zinc, argon, helium, nitrogen, carbon dioxide, nitric oxide, nitrogen dioxide, ozone, phosgene, hydrogen and fluoride.
The composition of fumes depends on the materials being welded. Steel welding, for instance, produces fumes that mostly contain iron, along with small amounts of chromium, nickel, manganese, molybdenum, vanadium, titanium, cobalt and copper. Fumes arising from stainless steel welds have a large amount of chromium or nickel and a small amount of iron.
Longer Exposures Lead To More Serious Health Problems
Exposure to welding fumes and gases may be acute or prolonged. Acute exposure can cause eye, nose and throat irritation, dizziness and nausea. (Workers who experience these symptoms should leave the area immediately and obtain medical attention.)
Prolonged exposure may cause lung damage; lung, larynx and urinary tract cancers; stomach ulcers, kidney damage and nervous system damage. The table below lists some of the hazardous materials found in welding and the potential health effects that acute or prolonged exposure to them can cause.
|zinc oxide||metal fume fever|
|manganese fume||Parkinson’s–like symptoms|
|helium, argon, and carbon dioxide||suffocation|
|hexavalent chromium||damage to the eyes, skin, nose, throat, and lungs; cancer|
|ozone||headaches, dry eyes, lung damage|
|cadmium oxides||respiratory and throat irritation, chest pain, breathing difficulty, kidney damage, emphysema; suspected carcinogen|
|zinc||metal fume fever|
|hydrogen fluoride||eye and respiratory tract irritation, lung, kidney, bone and liver damage, chronic irritation of the nose, throat and bronchi|
|copper||nausea, irritation of the eyes, nose and throat, metal fume fever|
|lead||lasting damage to the nervous system, kidneys, digestive system and cognitive function; lead poisoning|
Factors that affect worker exposure to welding fume include: the type of welding process used; the kind of base and filler metals used; the composition of the welding rod; the welder’s work practices; the location in which the welding is done (outside, or in an enclosed space); the air movement in that location and the use of ventilation controls.
In addition to the energy sources mentioned above, a laser, an electron beam, friction, and ultrasound are also used in welding.
Ways To Reduce Worker Exposure To Welding Fume
Proper ventilation is important to reducing fume and gas levels in a workspace. Welding should not be done in confined spaces that lack sufficient ventilation. Even in outdoor or open workspaces, care should be taken to ensure adequate ventilation. For instance, when welding outdoors, workers should position themselves both upwind ― in order to avoid breathing welding fumes and gases ― and from other workers. In other scenarios, local exhaust ventilation systems can help remove toxic gases from the welder’s breathing zone.1
Additional Tips for Reducing Exposure To Hazardous Fumes:
- Keep fume hoods, extractor guns and vacuum nozzles close to the plume source
- Keep exhaust ports away from other workers
- Substitute a lower fume-generating welding type
- Clean solvent residue and paint from welding surfaces
- Use respiratory protection if work practices and ventilation strategies fail to reduce exposures to safe levels. The Permissible Exposure Limit (PEL) for hexavalent chromium, for example is 5 µg/ m3 as an 8-hour time-weighted average*. (Respiratory protection should not be used to replace the use of mechanical ventilation.)
- Follow manufacturer’s instructions and safety data sheets (SDSs)
- Do not weld near degreaser solvents, whether they are on surfaces or in baths
- Use substitute materials such as water-based cleaners or high flash point solvents.
OSHA’s Hazard Communication standard (29 CFR 1910.1200) requires employers to make welders aware of the hazards of the materials with which they are working.
Other relevant OSHA regulations: *29 CFR 1910.1026 and 1926.1126, which address worker exposure to Hexavalent chromium, 29 CFR 1910 Subpart Q; 29 CFR 1926 Subpart J; 29 CFR 1915 Subpart D; 29 CFR 1910.146; 29 CFR 1915 Subpart B and 29 CFR 1910.134. WMHS