In brief
Welding fume consists of respirable metal oxide particles and gases such as ozone and nitrogen oxides; in 2017 IARC classified welding fume as carcinogenic to humans (Group 1). The composition of the fume depends on the material being welded and its volume on the welding process. Extraction at source comes first: on-torch extraction for MIG/MAG and flux-cored wire, and a mobile extraction arm held close to the weld point for other work; respiratory protection complements these.
What is welding fume and how does it form?
Welding fume is made up of very fine particles formed when metal vaporised at arc temperature comes into contact with air and condenses, together with gases formed around the arc. Most of the particles are respirable; in other words, they can reach deep into the lungs without being trapped in the nose and upper airways. The gas components are:
- Ozone: Formed when arc light acts on oxygen in the air; particularly pronounced in TIG and in MIG welding of aluminium. It irritates the eyes and airways.
- Nitrogen oxides: Formed from nitrogen and oxygen in the air at high temperatures.
- Carbon monoxide: Can form when carbon dioxide shielding gas decomposes in the arc; it accumulates in enclosed and confined spaces.
In metal and machinery manufacturers in Bursa and the surrounding provinces, on the chassis and exhaust component lines of the automotive supply industry and in steel construction workshops, welding is one of the most common jobs. We covered the welder's arc radiation, burn and electrical risks in our article on welders' risks; this article focuses on the health effects of fume and the choice of extraction systems.
Is welding fume carcinogenic?
Yes. In 2017 the International Agency for Research on Cancer (IARC) classified welding fume as carcinogenic to humans (Group 1); in the same evaluation, ultraviolet radiation emitted during welding was also placed in Group 1. This classification applies to welding fume in general, including carbon steel welding, not only to stainless steel welding.
The risk is even higher with stainless steel and high-alloy materials, because the fume contains hexavalent chromium compounds and nickel compounds. IARC also regards these compounds as carcinogenic to humans. The practical consequence is this: welding fume must be managed not as a "nuisance fume" but as a carcinogenic exposure. That makes extraction at source the rule, not the exception.
Metal oxides and health effects
The composition of the fume varies with the material being welded, the filler wire and the surface coating:
| Material welded | Prominent component in the fume | Possible health effect |
|---|---|---|
| Carbon steel | Iron oxide, manganese | Iron dust deposits in the lungs with long-term exposure (siderosis); nervous system effects from manganese |
| Stainless steel | Hexavalent chromium, nickel | Lung cancer, respiratory and skin sensitisation, asthma |
| Galvanised sheet | Zinc oxide | Metal fume fever |
| Aluminium | Aluminium oxide, high ozone | Respiratory tract irritation |
| Cadmium-plated or lead-painted parts | Cadmium, lead | Acute lung damage, kidney and blood effects |
| Oily, painted or primed surfaces | Organic decomposition products | Irritation, headache, respiratory complaints |
Chronic bronchitis, reduced lung function and susceptibility to pneumonia can also be seen in people who have welded for many years. Sensitisation from stainless steel welding can develop into occupational asthma.
Metal fume fever
Metal fume fever is a flu-like condition caused by inhaling zinc oxide fume, particularly when welding, cutting or grinding galvanised sheet. Symptoms begin a few hours after exposure, so they often appear at the end of the shift or in the evening:
- Metallic taste in the mouth, dry throat,
- Fever, shivering, sweating,
- Muscle and joint pain, fatigue,
- Cough, a feeling of tightness in the chest, headache.
The condition usually resolves by itself within a day or two. It is typically more pronounced at the start of the week after a weekend break. However, it should not be dismissed on site as "welder's fever, it'll pass": the symptoms are a warning sign that the worker has been exposed to heavy fume without extraction. Fume from more toxic metals such as cadmium can give similar symptoms at first but can lead to severe lung damage. A worker reporting these complaints should be referred to the workplace physician and the extraction arrangement for their work reviewed immediately. For the other risks in plants where galvanised material is produced, see our article on galvanising and electroplating.
Fume volume by welding process
Even on the same material, the amount of fume varies markedly with the welding process:
| Process | Fume generation | Note |
|---|---|---|
| Flux-cored wire (FCAW) | High | Very dense fume on thick welds and at high current |
| Manual metal arc (MMA) | High | The electrode coating contributes to the fume; on-torch extraction cannot be used |
| MIG/MAG (GMAW) | Medium | Increases with current and arc type; spray arc produces more fume than short-circuit arc |
| TIG (GTAW) | Low | Little fume but high ozone and UV, especially on aluminium |
| Submerged arc (SAW) | Very low | The arc stays under the flux layer |
| Carbon arc gouging, plasma cutting | Very high | Not welding, but the densest fume source in the same workshop |
Other factors that increase fume volume: high current, long arc length, coated surfaces, the welder's head being in the fume plume, and working in enclosed or confined spaces. This table can be used in the risk assessment to decide which station has priority.
Welding fume extraction: on-torch or mobile?
Art. 7 of the Regulation on Health and Safety Measures in Work with Chemical Substances requires that, where substitution is not possible, engineering controls and measures at source are applied first, and personal protection only if these are insufficient. Annex I, Art. 2.5.1 of the Regulation on Work Equipment also requires work equipment that presents a hazard from gas, vapour or dust release to be fitted with systems that contain or extract them at source.
| System | Best suited to | Strength | Point to watch |
|---|---|---|---|
| On-torch extraction | MIG/MAG and flux-cored wire; repeated welds in series production | The extraction nozzle moves with the weld point; the welder does not need to reposition anything | The torch becomes heavier and the hose bulkier; the extraction rate must be set so as not to disturb the shielding gas |
| Mobile extraction arm | MMA, TIG, repair and maintenance welding, parts of varying sizes | Can be used with any process | Effectiveness drops quickly if the hood is not kept close to the weld point; the welder must move the arm for each new weld |
| Downdraught welding table | Welding of small parts on the table | Less dependent on the welder's position | Inadequate for large parts |
| General ventilation | Complementary | Reduces the remaining fume in the room | On its own it does not protect the air the welder breathes |
The most common mistake with a mobile arm is leaving it a metre away from the weld point. Capture velocity drops very quickly with distance from the hood; keep the hood at roughly one hood diameter away and on the side where the fume plume rises. Remember that filtered mobile units return air to the room: for stainless steel welding, prefer a system that exhausts outside wherever possible, keep to the filter change interval and dispose of used filters in sealed bags as waste containing carcinogens.
Welding masks and respiratory protection
If extraction at source does not provide full protection, for example in confined spaces, in on-site assembly welding or with stainless steel, respiratory protection is added:
- A dust mask that can be worn under the welding helmet: FFP2 or FFP3 class for particulates. We explained class selection in our article on choosing a dust mask.
- Powered air-purifying welding helmet: Systems that supply filtered air to the welding helmet provide comfort and protection during long welding sessions; they stand out for stainless steel welding.
- Watch out for gases: Particulate filters do not capture ozone, nitrogen oxides or carbon monoxide. Where there is a gas risk in a confined space, ventilation and measurement are essential; for confined space rules, see our article on working in confined spaces.
A beard prevents tight-fitting masks from sealing on the face. PPE is issued after the worker has been trained in its use and is tracked with an issue record.
Measurement and health surveillance
The level of exposure to welding fume can be measured by personal sampling. We plan measurements with authorised laboratories and health institutions and enter the results into the risk assessment; a measurement taken after the extraction system is installed shows the effect of the measure.
In health surveillance, the workplace physician takes into account the material the worker welds, the process and the duration. Lung function tests, chest X-rays and other investigations have no fixed frequency in the legislation; the physician decides according to the risk. Complaints of metal fume fever, shortness of breath or recurrent bronchitis should be asked about specifically during examinations. You can find how test results are read in our article on lung function testing.
We carry out welders' health surveillance through our health surveillance service, and the assessment of welding stations and extraction priorities as part of risk assessment. For other risks in the sector, see our metal and machinery page.
Frequently Asked Questions
Is welding fume carcinogenic?
Yes. In 2017 IARC classified welding fume as carcinogenic to humans (Group 1). The hexavalent chromium and nickel compounds formed in stainless steel welding are also carcinogenic.
Is metal fume fever dangerous?
It usually passes within a day or two, but it shows that the worker has been exposed to heavy fume without extraction. A worker reporting symptoms should be referred to the workplace physician and the extraction arrangement corrected immediately. With metals such as cadmium, similar symptoms can be the start of severe lung damage.
Should on-torch or mobile extraction be chosen?
In MIG/MAG and flux-cored wire welding, on-torch extraction usually gives more consistent results because it does not require the welder to reposition anything. In MMA, TIG and repair welding, a mobile extraction arm kept close to the weld point is used.
Does a welding mask protect against fume?
A standard welding helmet protects the eyes and face from arc radiation; it does not filter fume. For fume, an FFP2 or FFP3 class dust mask under the helmet or a welding helmet with a filtered air supply is used.
An exposure-based test plan, pre-employment and periodic examinations, confidential health files and an examination schedule tracked per person.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.