Welding fumes are widely known for their effects on health, and when carried out in a confined or inadequately ventilated area, the risk and exposure to these harmful fumes dramatically increases. If you find lingering smoke in your workspace several minutes after the welding process is complete, it is a clear indication of insufficient ventilation.

Confined spaces, such as tanks, wells, tunnels, ship holds, ditches, culverts, vaults, silos, or maintenance holes naturally lack proper ventilation. Therefore, there is not only the health risk from inhaling welding fumes but also an increased likelihood of gas, steam, or dust accumulation leading to potential fire, detonation, or explosion. This is the reason OSHA firmly disapproves of welding without adequate ventilation in confined spaces.

Performing welding in an inadequately ventilated area can increase health risks as hazardous substances are found in higher concentrations. These effects can range from mild irritation to cancer, or even fatal outcomes. Organizations are obligated to keep pollutants below the limits set by law, and welding fume extractors are the most effective method for achieving this.

This article delves into the risks associated with welding in poorly ventilated areas, offering straightforward solutions for worker protection.

Welding Fume Composition and Impacts

When a metal is heated beyond its boiling point, fumes form as its vapors condense into very fine particles. These fumes comprise a mix of metals and gases. The effects of welding fumes on the individual breathing them in vary depending on their composition. Some examples include:

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

The composition of welding fumes is influenced by numerous factors, such as the welding process, base and filler materials, flux, electrode, shielding gas, and coatings like paint, lubricant, or solvent. For instance, stainless steel can generate hexavalent chromium and nickel in the fume, while aluminum welding fumes may contain significant quantities of aluminum oxide and ozone. Plated, galvanized, or painted metals can produce cadmium, zinc oxide, or lead fumes.

Welding fume particles range in size between 0.005 and 20 µm, with the majority being smaller than 1 µm. Inhaled particles may deposit throughout the respiratory system, including the gas-exchange region of the lungs.

The only reliable way to determine the substances in welding fumes and their concentration is through air sampling. The sampler is placed beneath the welder’s helmet to assess the level of hazardous substances in his breathing zone. This information will allow you to identify the substances that need to be regulated. Welding fume sampling should only be conducted by appropriately trained personnel.

Health Risks Linked to Inhaling Welding Fumes in Poorly Ventilated Areas

All health risks described in this section are intensified due to the work being performed in a confined space or poorly ventilated area, making the implementation of corrective measures vital.

OSHA suggests that inhaling welding fumes could lead to health problems such as:

  • Irritation of eyes, nose, and throat
  • Dizziness and nausea
  • Breathing difficulties potentially leading to suffocation or asphyxiation
  • Metal fume fever
  • Lung damage and various types of cancer
  • Stomach ulcers
  • Kidney damage
  • Damage to the nervous system

The Centers for Disease Control and Prevention (CDC) has also examined the effects of inhaling manganese. Long-term exposure to manganese fume can result in Parkinson-like symptoms, fertility issues, mood changes, short-term memory alterations, slower reaction times, and impaired hand-eye coordination. Read our post about the dangers of manganese fumes to learn more.

According to a study by the International Agency for Research on Cancer (IARC), validated by the Centers for Disease Control and Prevention (CDC), welding fumes are classified as carcinogenic to humans (Group 1).

In Canada, the CNESST adds the following potential health risks to consider:

  • Chest pain
  • Asthma
  • Hemorrhages
  • Dermatitis or eczema
  • Kidney diseases
  • Bone and joint disorders
  • Siderosis (iron oxide in lung tissue post-inhalation)
  • Stannosis (tin oxide in lung tissue post-inhalation)
  • Anthracosis (poisoning post carbon dust inhalation)
  • Berylliosis (poisoning post beryllium dust inhalation)
  • Accumulation of fluid in the lungs

Read more about what to do if you inhale welding fumes or the dangers and toxicity of welding fumes..

How to Ensure Safe Welding Practices in a Poorly Ventilated Area?

Basic questions

To address this issue, two fundamental questions should be asked:

  1. Is the area poorly ventilated due to lack of feasible options for adequate ventilation? Often, inadequate ventilation is due to management decisions that could be corrected with some investments. Even confined spaces can be ventilated using a large hose connected to a fan at one end and lowered into a manhole at the other. The fan outside the confined space will expel harmful gases and vapors, while fresh air should be drawn in through an air intake.
  2. The second question is whether welding in this area is indispensable. It might be possible to replace welding operations with another process or relocate the welding activity to a different area.

Welding Fume Extractors are Essential in Poorly Ventilated Areas

The most effective method to protect welders and their coworkers from welding fumes is by using fume extractors. For MIG welding, fume extraction MIG guns are the most efficient solution. They can be utilized with portable vacuum units or a centralized vacuum system and can even be used in confined spaces.

Another alternative is a fume extraction arm. This technology is the most popular and probably the best for every process except MIG welding, where a fume extraction gun would be superior. However, flexible arms can’t be used in most confined or cluttered spaces.

Lastly, fume extraction nozzles can be used. They are smaller and less expensive but require frequent repositioning during work due to their limited efficiency area. Nevertheless, they are a viable alternative in confined spaces if fume extraction MIG guns are not suitable.

We have a detailed blog post about the different types of welding fume extractors and how to choose the best one for your application if you are interested.

Producing Less Toxic Fume

The subsequent step would be to evaluate if the process could generate less toxic fume. A good way to do that is to explore different solutions with your engineers and suppliers. For instance, all paint, lubricant, or solvent should be removed from the parts that will be welded. Changing the base and filler materials, shielding gas, wire, etc., could also be considered.

Personal Protective Equipment

If, after implementing these solutions, you still fail to meet air quality standards, you must provide your welders with personal protective equipment (PPE). This could be a simple N95 or N99 disposable mask, a reusable respirator with filters, a welding helmet with a powered air filtration system, or a welding helmet with an external air supply system.

The PPE and filters required will depend on the hazardous substances present in the fume and their concentration in the welder’s breathing zone.



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Air Quality Standards for Welding in Poorly Ventilated Areas

In the US, OSHA has established a Permissible Exposure Limit (PEL) for welding fumes of 5 mg/m3. This is the average concentration of the substance over 8 hours within the welder’s breathing zone. Certain substances found in welding fumes must also be kept below their PEL. For example, Hexavalent Chromium has a PEL of 5 μg/m3 as an 8-hour time-weighted average. The welding process’s components will need to be analyzed to determine which substances must be monitored. Sampling the welding fume may also be necessary. It’s also crucial to know that OSHA prohibits welding in confined spaces without ventilation.

ACGIH recommends a threshold limit value of 0.02 mg/m3 of manganese oxide in the welder’s breathing zone to avoid long-term effects on the nervous system.

Each province or territory in Canada has its exposure limit, typically between 3 and 10 mg/m3. Some jurisdictions distinguish between inhalable and respirable particles. Moreover, several toxic substances found in welding fumes (such as chromium, zinc, cadmium, lead, ozone, nitrogen oxides, or nickel) also have their concentration limits.

Here are the exposure limits for welding fumes in each Province and Territory in Canada.

  • TWA: Time-Weighted Average over 8 hours
  • STEL: Short-Term Exposure Limit (maximum for 15 minutes, no more than four times per day with at least 60 minutes in between)
  • C: Ceiling (must never be exceeded)
  • (i): Inhalable particles (smaller than 100 µm)
  • (r): Respirable particles (smaller than 4 µm)
  • ALARA: As low as reasonably achievable
BC 10mg/m3(i)*
3 mg/m3(r)*
NB 10mg/m3(i)*
NL 10mg/m3(i)*
3 mg/m3(r)*
QC5mg/m315mg/m3 **25mg/m3
* Based on ACGIH recommendations.
** For 30 minutes during a workday.

It is impossible to achieve these results in a confined space or poorly ventilated area without welding fume extractors. Even in a well-ventilated area, they are needed most of the time. The lack of ventilation merely amplifies the concentration of hazardous substances in the welder’s breathing zone, escalating the risks and the likelihood of potential health issues.

Additional Hazards of Welding in a Poorly Ventilated Area

When welding fumes and other substances are not properly removed from a facility, gas, steam, or dust could accumulate. This could lead to a fire, deflagration, or explosion, depending on the particles present in the air. Once again, air sampling might be necessary to assess the risk and implement suitable measures to prevent accidents.

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.