Can the composition of welding fumes vary?
Yes, the composition of welding fumes is determined by the metals in the material being welded, the composition of the electrode, coatings, and other factors such as:
- context Fluxes containing silica or fluoride produce amorphous silica, metallic silicates and fluoride fumes.
- context Fumes from mild steel welding contain mostly iron with small amounts of additive metals (chromium, nickel, manganese, molybdenum, vanadium, titanium, cobalt, copper etc.).
- context Stainless steels can have larger amounts of chromium, including hexavalent chromium or nickel in the fume and lesser amounts of iron.
- context Nickel alloys have much more nickel in the fume and very little iron.
How do coatings affect the composition of welding fumes?
Vapours or fumes can come from coatings and residues on metal being welded. Some ingredients in coatings can have toxic effects. These ingredients include:
- context metal working fluids, oils, and rust inhibitors
- context zinc on galvanized steel (vaporizes to produce zinc oxide fume)
- context cadmium plating
- context chromates
- context vapours from paints and solvents
- context lead oxide primer paints
- context plastic coatings
What are examples of welding gases?
Gases used in welding and cutting processes include:
Gases produced from welding and cutting processes include:
Gases are also produced from the thermal breakdown of coatings:
- context shielding gases such as carbon dioxide, argon, helium, etc.
- context fuel gases such as acetylene, propane, butane, etc.
- context oxygen, used with fuel gases and also in small amounts in some shielding gas mixtures
- context carbon dioxide from the decomposition of fluxes
- context carbon monoxide from the breakdown of carbon dioxide shielding gas in arc welding
- context ozone from the interaction of electric arc with atmospheric oxygen
- context nitrogen oxides from the heating of atmospheric oxygen and nitrogen
- context hydrogen chloride and phosgene are produced by the reaction between ultraviolet light and the vapours from chlorinated hydrocarbon degreasing solvents (e.g., trichloroethylene, TCE)
- context Polyurethane coatings can produce hydrogen cyanide, formaldehyde, carbon dioxide, carbon monoxide, oxides of nitrogen, and isocyanate vapours.
- context Epoxy coatings can produce carbon dioxide and carbon monoxide.
- context Vinyl paints can produce hydrogen chloride.
- context Phosphate rust-inhibiting paints can release phosphine during welding processes.
- context Minimizing exposure to degreasing solvent vapours.
What are the health effects of welding fumes and gases?
The International Agency for Research on Cancer (IARC) has classified welding fumes as carcinogenic to humans (Group 1). IARC describes welding fumes as consisting mainly of fine solid particles (with an aero-dynamic diameter of less than 1 µm), and as a complex mixture of particles from the wire or electrode, base metal, or any coatings on the base metal. They consist mainly of metal oxides, silicates, and fluorides.
Source: Tables 1 to 3 are from Work Safe Alberta's Welder's Guide to Hazards of Welding Gases and Fumes, 2009
- chemical Fume Type | Source | Health Effect
- general Aluminum | Aluminum is a component of some alloys, e.g., inconels, copper, zinc, steel, magnesium, brass and filler materials. | Respiratory irritant.
- chemical Beryllium | Hardening agent found in copper, magnesium, aluminum alloys and electrical contacts. | "Metal Fume Fever." A carcinogen. Other chronic effects include damage to the respiratory tract.
- general Cadmium Oxides | Stainless steel containing cadmium or plated materials, zinc alloy. | Irritation of the respiratory system, sore and dry throat, chest pain and breathing difficulty. Chronic effects include kidney damage and emphysema. Suspected carcinogen.
- general Chromium | Most stainless-steel and high-alloy materials, welding rods. Also used as plating material. Converts to hexavalent chromium during welding. | Increased risk of lung cancer. Some individuals may develop skin irritation. Some forms are carcinogens (hexavalent chromium).
- chemical Copper | Alloys such as Monel, brass, and bronze. Also some welding rods. | Acute effects include irritation of the eyes, nose and throat, nausea and "Metal Fume Fever."
- safety Fluorides | Common electrode coating and flux material for both low- and high-alloy steels. | Acute effect is irritation of the eyes, nose and throat. Long-term exposures may result in bone and joint problems. Chronic effects also include excess fluid in the lungs.
- safety Iron Oxides | The major contaminant in all iron or steel welding processes. | Siderosis – a benign form of lung disease caused by particles deposited in the lungs. Acute symptoms include irritation of the nose and lungs. Tends to clear up when exposure stops.
- chemical Lead | Solder, brass and bronze alloys, primer/coating on steels. | Chronic effects to the nervous system, kidneys, digestive system and mental capacity. Can cause lead poisoning.
- chemical Manganese | Most welding processes, especially high-tensile steels. | “Metal Fume Fever.” Chronic effects may include central nervous system problems.
- safety Molybdenum | Steel alloys, iron, stainless steel, nickel alloys. | Acute effects are eye, nose and throat irritation, and shortness of breath.
- safety Nickel | Stainless steel, Inconel, Monel, Hastelloy and other high-alloy materials, welding rods and plated steel. | Acute effect is irritation of the eyes, nose and throat. Increased cancer risk has been noted in occupations other than welding. Also associated with dermatitis and lung problems.
- safety Vanadium | Some steel alloys, iron, stainless steel, and nickel alloys. | Acute effect is irritation of the eyes, skin and respiratory tract. Chronic effects include bronchitis, retinitis, fluid in the lungs and pneumonia.
- chemical Zinc | Galvanized and painted metal. | Metal Fume Fever.
- chemical Gas Type | Source | Health Effect
- biological Carbon Monoxide | Formed in the arc. | Absorbed readily into the bloodstream, causing headaches, dizziness or muscular weakness. High concentrations may result in unconsciousness and death
- general Hydrogen Fluoride | Decomposition of rod coatings. | Irritating to the eyes and respiratory tract. Overexposure can cause lung, kidney, bone and liver damage. Chronic exposure can result in chronic irritation of the nose, throat and bronchi.
- general Nitrogen Oxides | Formed in the arc. | Eye, nose and throat irritation in low concentrations. Abnormal fluid in the lung and other serious effects at higher concentrations. Chronic effects include lung problems such as emphysema.
- chemical Oxygen Deficiency | Welding in confined spaces, and air displacement by shielding gas. | Dizziness, mental confusion, asphyxiation and death.
- safety Ozone | Formed in the welding arc, especially during plasma-arc, MIG and TIG processes. | Acute effects include fluid in the lungs and hemorrhaging. Very low concentrations (e.g., one part per million) cause headaches and dryness of the eyes. Chronic effects include significant changes in lung function.
- chemical Gas Type | Source | Health Effect
- chemical Aldehydes (such as formaldehyde) | Metal coating with binders and pigments. Degreasing solvents | Irritant to eyes and respiratory tract.
- chemical Diisocyanates | Metal with polyurethane paint. | Eye, nose and throat irritation. High possibility of sensitization, producing asthmatic or other allergic symptoms, even at very low exposures.
- chemical Phosgene | Metal with residual degreasing solvents. (Phosgene is formed by reaction of the solvent and welding radiation.) | Severe irritant to eyes, nose and respiratory system. Symptoms may be delayed.
- physical Phosphine | Metal coated with rust inhibitors. (Phosphine is formed by reaction of the rust inhibitor with welding radiation.) | Irritant to eyes and respiratory system, can damage kidneys and other organs.
How can I prevent exposure to welding fumes and gases?
It is important to follow the manufacturer's instructions, safety data sheets (SDSs), and hazard control measures to minimize the risks and hazards of welding fumes and gases.
- substitution Use substitute materials such as water-based cleaners or high flash point solvents.
- substitution Consider using a lower fume-generating or less toxic process or material
- requirement Cover the degreaser baths or containers.
- requirement Do not weld on surfaces that are still wet with a degreasing solvent.
- requirement Do not weld near degreasing baths.
- requirement Do not use chlorinated hydrocarbon degreasers.
- requirement Safely remove coatings before welding.
- engineering Have adequate ventilation in a workplace to prevent the displacement or enrichment of oxygen and to prevent the accumulation of hazardous substances and flammable atmospheres.
- engineering Use local exhaust ventilation systems positioned close to the plume source to remove fumes and gases from the welder’s breathing zone.
- engineering Wear appropriate respiratory protective equipment according to your company’s respiratory protection program. Respiratory protective equipment should not replace mechanical ventilation.
- administrative Following safe work procedures, such as workers positioning themselves to avoid breathing welding fumes and gases
- requirement Risk assessments and occupational hygiene sampling can be performed to determine potential worker exposures and other hazards and to help identify the control measures that are needed. See the applicable occupational exposure limits in your jurisdiction.