Since the 1980s, we have led the way in North America, offering solutions for welding fume extraction. This blog post outlines the exposure limits in the Northwest Territories for various commonly encountered hazardous gases and metals in welding fume.

When a metal is heated beyond its boiling point, it creates fumes as the vapors cool and condense into extremely tiny particles. These particles range in size from 0.005 to 20 µm, with the majority being less than 1 µm, small enough to spread throughout the respiratory system.

The composition of fume is determined by factors such as the material being welded, the electrode, the coatings, the flux, and the shielding gas, among others. Air sampling is typically required to identify the hazardous and regulated substances in your workplace. However, initial understanding can be gained from information about the metals, gases, and consumables used in the welding process.

What particles found in welding fume are potentially harmful?

The following list includes some of the hazardous gases and metals commonly present in welding fume, which we will discuss in this post:

  • Aluminum
  • Antimony
  • Arsenic
  • Beryllium
  • Cadmium
  • Chromium
  • Cobalt
  • Copper
  • Iron oxide
  • Lead
  • Manganese (learn more about manganese in welding fumes)
  • Molybdenum
  • Nickel
  • Silver
  • Tin
  • Titanium dioxide
  • Vanadium
  • Zinc
  • Argon
  • Carbon Dioxide
  • Carbon Monoxide
  • Helium
  • Hydrogen Fluoride
  • Nitric Oxide
  • Nitrogen
  • Nitrogen Dioxide
  • Ozone
  • Phosgene

Occupational Health and Safety Regulations for Welding Fume in Northwest Territories

In the Northwest Territories, employers are required to abide by the Occupational Health and Safety Regulations.

Part 6 (General Health Requirements) contains the regulations regarding ventilation, which are especially pertinent for welding. Some of these regulations are quoted below.

“An employer shall ensure the adequate ventilation of a work site; and, to the extent that is reasonably possible, render harmless, and prevent the accumulation of, any contaminants or impurities in the air by providing an adequate supply of clean and wholesome air and maintaining its circulation throughout the work site.”

“An employer shall provide a mechanical ventilation system at a work site that is sufficient and suitable to protect workers against inhalation of a contaminant and to prevent accumulation of the contaminant […] if any work, activity or process at the work site gives off a dust, fume, gas, mist, aerosol, vapour or other airborne contaminant that is hazardous to workers.”

“An employer shall, to the extent that is reasonably possible, ensure that a mechanical ventilation system […] includes local exhaust ventilation that is installed and maintained at or near the point of origin of the contaminant so as to effectively prevent the contaminant from entering the air of the work site.”

Lastly, Contamination Limits can be located in Schedule O.

“If a chemical or biological substance set out in Schedule O is present at a work site, an employer shall, to the extent that is reasonably possible, provide adequate engineering controls to ensure that the contamination limit set out in Schedule O is not exceeded; and take steps to ensure that workers’ personal exposure does not exceed the contamination limits set out in Schedule O.”



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Contamination Limits for Welding Fume, Metals, and Gases in Northwest Territories

According to the Occupational Health and Safety Regulations, the subsequent limits are the relevant Contamination Limits (CL) for welding fume and its constituents in the Northwest Territories.

The abbreviations used in the ensuing tables are:

  • TWA: The Time-Weighted Average concentration for an 8-hour workday
  • STEL: Short-Term Exposure Limit (maximum time-weighted average concentration for 15 minutes)
  • C: Ceiling (concentration never to be exceeded)
Welding Fumes5mg/m310mg/m3
Cadmium, respirable**2µg/m36µg/m3
Chromium metal and (III)0.5mg/m31.5mg/m3
Chromium (VI), soluble0.05mg/m30.15mg/m3
Chromium (VI), insoluble0.01mg/m30.03mg/m3
Iron Oxide5mg/m310mg/m3
Molybdenum, inhalable*10mg/m320mg/m3
Molybdenum, respirable**3mg/m36mg/m3
Nickel, inhalable*1.5mg/m33mg/m3
Tin metal and oxide2mg/m34mg/m3
Titanium dioxide10mg/m320mg/m3
Vanadium pentoxide, respirable**0.05mg/m30.15mg/m3
Zinc oxide, respirable**2mg/m310mg/m3
* For inhalable fraction, see Table A of Schedule O
** For respirable fraction, see Table B of Schedule O
Carbon Dioxide5,000ppm30,000ppmNone
Carbon Monoxide25ppm190ppmNone
Hydrogen Fluoride0.5ppmNone2ppm
Nitric Oxide25ppm38ppmNone
Nitrogen Dioxide3ppm5ppmNone
* Simple asphyxiant: must be controlled to ensure that no atmosphere is oxygen deficient (less than 18% oxygen) at any time.

ACGIH – Threshold Limit Values for Welding Fume, Metals, and Gases

The American Conference of Governmental Industrial Hygienists (ACGIH) is a significant entity that studies hazardous materials and proposes exposure limits. Their recommendations influence numerous health and safety organizations throughout North America, thus, understanding their suggested Threshold Limit Values (TLV) is greatly beneficial.

ACGIH holds copyright over Threshold Limit Values and hence these cannot be copied onto other platforms. However, we have provided the relevant links to their website below for your convenience.

As ACGIH has not issued a specific recommendation for welding fumes, these are categorized under Particulates Not Otherwise Regulated. In such instances, the ACGIH proposes a TLV-TWAEV of 3mg/m3 for particles that can be inhaled and 10mg/m3 for particles that can be ingested.

* A concentration limit is not included because available oxygen is the limiting factor.

Health Risks Associated with Inhalation of Welding Fumes

As stated by entities like OSHA, the Centers for Disease Control and Prevention, the International Agency for Research on Cancer, and the CNESST (Quebec), the following health hazards could potentially arise from the inhalation of welding fumes:

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

These potential health risks underline the necessity to safeguard welders, adhere to the set standards, and strive for the highest possible efficiency in pollutant extraction. Welding fume extractors are considered the optimal method for this purpose.

For further insights on the regulations surrounding welding fumes in other Canadian provinces or territories, please refer to the following links to navigate to our respective articles on the subject:

Any Questions?

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