At Henlex, we have been protecting welders and their coworkers from welding fumes for over 40 years. Fumes are formed when a metal is heated above its boiling point, and its vapors condense into very fine particles. Their size ranges from 0.005 to 20 µm, but most are smaller than 1 µm and may deposit throughout the respiratory system.

Welding fumes are toxic regardless of the process and materials being used. Metal fume fever is the most common consequence of this toxicity. Welders should especially be avoiding and monitoring manganese, as well as carcinogenic agents, such as arsenic, hexavalent chromium, beryllium, or cadmium.

In the article, we will see how toxic welding fume is, what substances to be especially worried about, and how to reduce the risks for welders.

What types of welding produce toxic fumes?

Although it is only one variable of the equation, some welding processes produce less toxic fume than others. However, that does not mean that they do not require local exhaust ventilation to be within the permissible exposure limits, nor are they necessarily less dangerous.

But everything else being equal, it is interesting to know which welding and cutting process to favor if you have the option to choose:

  • Less fume: TIG, resistance welding, submerged arc, laser cutting
  • More fume: MIG, MAG, plasma cutting
  • The most fume: Stick welding, flux cored, arc gouging

The effects of welding fume

The composition of welding fumes is determined by many factors, including the welding process, base and filler materials, shielding gas, flux, consumables, plating, and coatings. Depending on its composition, it can have different effects on the person inhaling it. Here are a few examples:

  • Toxic: lead, manganese, cadmium, ozone, etc.
  • Carcinogenic: chromium, cadmium, beryllium, nickel, etc.
  • Metal fume fever: zinc, copper, magnesium, aluminum, cadmium, iron oxide, manganese, nickel, selenium, silver, tin, etc.
  • Allergens: chromium, nickel, zinc, aluminum, rosin, aminoethyl ethanolamine, diisocyanates, etc.
  • Asphyxiants: acetylene, argon, carbon oxides, nitrogen, helium, hydrogen, etc.
  • Fibrotic: asbestos, beryllium, iron, nitrogen oxide, silica, etc.
  • Irritants: ozone, nitrogen oxide, iron oxide, molybdenum, nickel, phosgene, phosphine, cadmium, chromium, copper, manganese, magnesium, molybdenum, zinc, hydrochloric acid, hydrofluoric acid, diisocyanates, aldehydes, tungsten, etc.

Metal fume fever

Metal fume fever is probably the most common occupational disease amongst welders and is undeniable proof that welding fume is toxic. Hundreds of documented cases of metal fume fever occur annually in the USA only.

Flu-like symptoms such as fever, chills, joint pains, muscle pain, headache, cough, nausea, and malaise typically occur 4 to 10 hours after exposure to toxic welding fume. But symptoms could be worse if the intoxication is more severe.

As reported by, metal fume fever is typically a benign disease with spontaneous resolution of symptoms after 12 to 48 hours following cessation of exposure. But it does have the potential to be serious, especially for workers with pre-existing medical conditions.

Cancer and welding fume

According to the International Agency for Research on Cancer (IARC), welding fumes are a group 1 carcinogenic to humans, regardless of the process used or the type of metal welded. Breathing toxic welding fume increases the risk of developing different types of cancer, such as lung cancer, mesothelioma, throat cancer, bladder cancer, and kidney cancer.

The American Conference of Governmental Industrial Hygienists (ACGIH) has also classified multiple substances found in welding fume as carcinogenic.

Arsenic in welding fume

Arsenic is used to manufacture alloys, generally lead or copper. It can sometimes be found in welding fume and is a confirmed human carcinogen.

Beryllium in welding fume

Beryllium can be found in welding fume as it is used as a hardening agent for copper, nickel, magnesium, and aluminum alloys and for electrical contacts (high heat capacity). It is a confirmed human carcinogen and one of the agents causing metal fume fever.

Cadmium in welding fume

Cadmium oxides can be found in welding fume as some stainless steels and zinc alloys contain cadmium. It is also used in coatings and plating. Cadmium is also an impurity in non-ferrous metals (zinc, lead, and copper), iron, and steel. It is classified as a suspected human carcinogen.

Hexavalent chromium in welding fume

Hexavalent chromium can be found in fumes when welding most stainless steels and high-alloy materials. Chromium is also used in the composition of welding rods or as a plating material. It is converted to a hexavalent state by high temperatures. Hexavalent chromium is a known carcinogen for humans.

We have a whole article about welding fume and cancer risks if you want to learn more.

Manganese and welding fume

Most welders are exposed to manganese. Its fumes are especially problematic with high-tensile and low-alloy steels, ferrous alloys, or some copper, aluminum, and nickel alloys. The amounts of manganese in the welding wire, rods, and flux are also significant.

When heated, manganese produces toxic fumes which can have devastating health effects if inhaled for a prolonged period. Prolonged exposure to fume with a manganese concentration over 1 mg/m3 can cause Parkinson–like symptoms. This progressive and disabling neurological condition due to an accumulation of manganese in the brain is called Manganism.

Symptoms may include trembling, stiffness, slow movements, poor balance, depression, anxiety, and hostility. The disease can appear after welding for a few months for some people. For others, it can be after 10 or 20 years.

On top of that, workers exposed to levels of manganese lower than 0.2 mg/m3 could suffer the following symptoms: changes in mood, short-term memory loss, reduced coordination, and altered reaction time. Breathing manganese can also damage the lungs, liver, and kidneys and could create fertility problems for male welders. In addition, manganese is toxic, can cause lung irritation and pulmonary edema, and is an aggravating factor for metal fume fever.

If you want to learn more about the effects of manganese on welders and permissible exposure limits in your jurisdiction, we have written an article on the subject.

If you have any questions about welding fume, do not hesitate to contact us. We will be happy to give you some insight, and we can even visit you for free in the US and Canada.

Henlex Inc.

Health issues caused by toxic welding fume

According to OSHA, the Centers for Disease Control and Prevention, the International Agency for Research on Cancer, and the CNESST (Canada), breathing welding fumes could cause the following health effects:

  • Eye, nose, and throat irritation
  • Dizziness and nausea
  • Breathing difficulties that could lead to suffocation or asphyxiation
  • Metal fume fever
  • Lung damage
  • Stomach ulcers
  • Kidney damage
  • Nervous system damage
  • Manganism
  • Chest pain
  • Asthma
  • Bleedings
  • Dermatitis or eczema
  • Kidney disease
  • Bone and joint disorders
  • Siderosis (iron oxide in lung tissue after inhalation)
  • Stannosis (tin oxide in lung tissue after inhalation)
  • Anthracosis (poisoning after inhalation of carbon dust)
  • Berylliosis (poisoning after inhalation of beryllium dust)
  • Accumulation of fluid in the lungs
  • Different types of cancer

How to avoid breathing toxic welding fumes

Here are a few tips to sustainably protect welders and other workers around from cancer and other health problems caused by welding fume:

  1. Only weld when it is necessary. Other processes can sometimes replace manual welding (bolts, fasteners, robotic welding).
  2. Isolate welding operations from other workers (have an area or building dedicated to welding only, for example, or at least use welding screens).
  3. Use welding processes that produce less fume. You could also change the power settings to reduce fumes.
  4. Use consumables and materials that produce less toxic fume. For example, you should remove paint or coatings. Avoid carcinogenic and toxic substances.
  5. Use welding fume extractors. For more information, see our general article about welding fume extractors or MIG welding fume extraction if that’s the process you are using.
  6. Make sure welders position themselves to avoid breathing fumes and gases. For example, they should not leave their head between the weld pool and the fume extractor. Or they can use the wind to drive the fumes away when welding outside.
  7. Make sure your factory is adequately ventilated.
  8. Use personal protective equipment such as masks and respirators if the previous measures are insufficient to reduce exposure to safe levels. They should be fitted for each worker individually.

Learn more about our step-by-step method to solve welding fume problems.

How much welding fumes can you breathe in before it becomes harmful?

Permissible exposure limits for welding fume, metal fume, and gases are regulated and are enforced by health and safety agencies like OSHA everywhere In North America. To know more about the maximum concentrations allowed, you can read one of the following articles:

In these articles, you will also find recommendations from the American Conference of Governmental Industrial Hygienists (ACGIH). These concentrations are considered safe nowadays if the welder does not work more than 8 hours a day and welds in a typical environment.

In the United States, the permissible exposure limit for welding fume enforced by OSHA and Cal/OSHA is 5 mg/m3. It is the 8 hours time-weighted average. In Canada, health and safety agencies in the Northwest Territories, Nunavut, Quebec, Saskatchewan, and Yukon set the exposure limit for welding fume at 5 mg/m3. Other provinces and territories follow the ACGIH recommendations, except for Alberta, which requires keeping it as low as reasonably possible.

Many hazardous substances found in welding fumes are also subjected to their exposure limit, such as chromium, manganese, etc.

Any Questions?

Feel free to contact us. We will help you protect your workers and comply with welding fumes standards anywhere in the US and Canada.