At Henlex, we’ve devoted over four decades to protecting welders and their colleagues from the dangers of welding fumes. These fumes are generated when metal is heated above its boiling point, causing its vapors to condense into small particles. Their size can vary from 0.005 to 20 µm, with most falling below 1 µm, which can deposit in various parts of the respiratory system.

Welding fumes are toxic regardless of the process and materials being used. Metal fume fever is a frequent consequence of this toxicity. Welders should especially be avoiding and monitoring manganese, along with carcinogenic substances such as arsenic, hexavalent chromium, beryllium, and cadmium.

In this article, we delve into the toxicity of welding fume, the substances to be particularly cautious about, and methods for reducing the risks for welders.

What welding processes produce toxic fumes?

While the process is only one factor, some welding techniques generate less toxic fumes than others. However, it’s important to remember that they still require local exhaust ventilation to comply with permissible exposure limits and they’re not necessarily less hazardous.

But everything else being equal, it’s helpful to understand which welding and cutting processes to prefer if given the choice:

  • 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 multiple factors, including the welding process, base and filler materials, shielding gas, flux, consumables, plating, and coatings. The effects of the fume on individuals who inhale it vary based on its composition. 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 likely the most prevalent occupational illness among welders, serving as clear evidence of the toxicity of welding fume. Every year in the U.S. alone, hundreds of cases of metal fume fever are officially recorded.

Flu-like symptoms such as fever, chills, joint and muscle pains, headache, cough, nausea, and general discomfort typically occur 4 to 10 hours following exposure to toxic welding fume. The severity of symptoms can escalate with increased exposure.

As reported by, metal fume fever generally poses a benign risk with symptoms naturally subsiding 12 to 48 hours after exposure ends. However, it can pose a serious risk, especially for workers with pre-existing health conditions.

Cancer and welding fume

The International Agency for Research on Cancer (IARC) classifies welding fumes as a group 1 carcinogen in humans, regardless of the process or type of metal welded. Inhalation of toxic welding fume heightens the risk of developing various cancers, such as lung, mesothelioma, throat, bladder, and kidney cancers.

The American Conference of Governmental Industrial Hygienists (ACGIH) has also categorized multiple substances in welding fume as carcinogens.

Arsenic in welding fume

Arsenic, typically used in the production of alloys, primarily lead or copper, can occasionally be present in welding fume and is a confirmed carcinogen in humans.

Beryllium in welding fume

Used as a hardening agent for copper, nickel, magnesium, and aluminum alloys and in electrical contacts (due to high heat capacity), beryllium can also be found in welding fume. It’s a proven human carcinogen and is one of the causative agents of metal fume fever.

Cadmium in welding fume

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

Hexavalent chromium in welding fume

Hexavalent chromium is 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.

For more information, we have a detailed article welding fume and cancer risks.

Manganese and welding fume

Manganese exposure is common amongst welders. Its fumes can pose significant health risks when working with high-tensile and low-alloy steels, ferrous alloys, or certain copper, aluminum, and nickel alloys. The quantity of manganese in welding wire, rods, and flux is also significant.

When heated, manganese produces toxic fumes that can have detrimental health effects if inhaled over a prolonged period. Prolonged exposure to fumes with a manganese concentration exceeding 1 mg/m3 can induce Parkinson-like symptoms. This debilitating neurological condition caused by an accumulation of manganese in the brain is known as Manganism.

Symptoms can include trembling, stiffness, slow movements, poor balance, depression, anxiety, and hostility. The disease can manifest after a few months of welding for some, while for others it can take 10 to 20 years.

Moreover, exposure to levels of manganese lower than 0.2 mg/m3 could trigger symptoms like mood changes, short-term memory loss, reduced coordination, and altered reaction time. Inhaling manganese can also damage the lungs, liver, and kidneys, potentially causing fertility issues for male welders. Additionally, manganese is toxic, can irritate the lungs and lead to pulmonary edema, and exacerbates metal fume fever.

For more information on the impacts of manganese on welders and the permissible exposure limits in your jurisdiction, check out our dedicated article.



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Health Risks Associated with 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 can lead to the following health conditions:

  • Eye, nose, and throat irritation
  • Dizziness and nausea
  • Breathing difficulties potentially leading to suffocation or asphyxiation
  • Metal fume fever
  • Lung damage
  • Stomach ulcers
  • Kidney damage
  • Nervous system damage
  • Manganism
  • Chest pain
  • Asthma
  • Bleeding
  • 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
  • Various types of cancer

Preventing Inhalation of Toxic Welding Fumes

Here are a few strategies to effectively protect welders and surrounding workers from the toxicity of welding fumes:

  1. Opt to weld only when necessary. Other methods such as bolts, fasteners, or robotic welding can often replace manual welding.
  2. Isolate welding operations from other workers (e.g., dedicate a specific area or building solely for welding, or at a minimum, use welding screens).
  3. Favor welding processes that generate fewer fumes. Adjusting power settings to decrease fumes can also be effective.
  4. Buy consumables and materials that yield less toxic fumes. For instance, remove paint or coatings and avoid carcinogenic and toxic substances.
  5. Deploy welding fume extractors. For more details, refer to our general article about welding fume extractors or the one specifically about MIG welding fume extraction.
  6. Ensure welders position themselves to avoid inhaling fumes and gases. For instance, they should not keep their head between the weld pool and the fume extractor. When welding outside, they can use the wind to carry the fumes away.
  7. Guarantee adequate ventilation in your workspace.
  8. If the previous measures are insufficient to reduce exposure to safe levels, use personal protective equipment such as masks and respirators, individually fitted for each worker.

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

Safe Exposure Limits for Welding Fumes

In North America permissible exposure limits for welding fume, metal fume, and gases are regulated and enforced by health and safety agencies like OSHA. To learn more about the maximum allowed concentrations, consider reading one of our following articles:

The articles also contain recommendations from the American Conference of Governmental Industrial Hygienists (ACGIH). These concentrations are considered safe under current standards, assuming the welder works no more than 8 hours per day 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, averaged over an 8-hour period. In Canada, health and safety agencies in the Northwest Territories, Nunavut, Quebec, Saskatchewan, and Yukon also enforce a limit for welding fume at 5 mg/m3. Other provinces and territories follow ACGIH recommendations, except for Alberta, which requires keeping it as low as reasonably achievable.

Several toxic substances found in welding fumes also have their specific exposure limits, 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.