The Dangers of Welding in a Confined Space

Welding fumes are notoriously harmful to our health, and working in a poorly ventilated area or confined space will increase the exposure and risk. Generally, if there is still some smoke in your working environment a few minutes after welders are done, it lacks ventilation.

Confined spaces such as tunnels, wells, maintenance holes, tanks, silos, culverts, ditches, vaults, or ship holds are poorly naturally ventilated. Therefore, on top of health risks from breathing welding fumes, there is a greater chance that gas, steam, or dust accumulation can cause a fire, deflagration, or explosion. That’s why OSHA does not tolerate welding without ventilation in confined spaces.

Welding in a poorly ventilated area amplifies health risks as the concentration of hazardous substances is higher. Effects range from mild irritation to cancer or even death. Companies must maintain pollutants below the limits imposed by the law. Welding fume extractors are the best way to do that.

These risks affect welders and other workers who are also exposed to welding fumes among other things. In this article, we will go into detail to explain the dangers of welding in a poorly ventilated area and introduce simple solutions to protect workers.

Welding fume composition and effects

Fumes are formed when a metal is heated above its boiling point, and its vapors condense into fine particles. It is a mix of metals and gases. Welding fumes can have different effects on the person inhaling them, depending on their composition. Here are a few examples:

• Asphyxiants: acetylene, argon, carbon oxides, nitrogen, helium, hydrogen
• Allergens: chromium, nickel, zinc, aluminum, rosin, aminoethyl ethanolamine, diisocyanates
• Fibrotic: 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
• Carcinogenic: chromium, cadmium, ozone, nickel
• Toxic: lead, manganese, cadmium, ozone
• Metal fume fever: zinc, copper, magnesium, aluminum, cadmium, iron oxide, manganese, nickel, selenium, silver, tin

The composition of welding fumes is determined by many factors, including the welding process, base and filler materials, flux, electrode, shielding gas, and coatings such as paint, lubricant, or solvent. For example, stainless steel can generate hexavalent chromium and nickel in the fume. Aluminum welding fumes can have significant amounts of aluminum oxide and ozone. Plated, galvanized, or painted metals can generate cadmium, zinc oxide, or lead fumes.

The size of welding fume particles ranges between 0.005 and 20 µm, the majority smaller than 1 µm. Inhaled particles may deposit throughout the respiratory system, including the gas-exchange region of the lungs.

The only way to know what substances are in welding fumes and their concentration would be to do some air sampling. The sampler is placed under the welder’s helmet to establish the amount of hazardous substances in his breathing zone. With this information, you will know which substances must be controlled. Sampling for welding fumes should only be performed by qualified personnel.

Health risks associated with breathing welding fumes in a poorly ventilated area

All the health risks introduced in this section are amplified by the fact that the work is performed in an enclosed space or a poorly ventilated area. Taking corrective measures is, therefore, of the highest importance.

According to OSHA, 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 and various types of cancer
• stomach ulcers
• kidney damage
• nervous system damage

The Centers for Disease Control and Prevention (CDC) has also studied the effect of inhaling manganese. Prolonged exposure to manganese fume can cause Parkinson–like symptoms, fertility problems, changes in mood and short-term memory, altered reaction time, and reduced hand-eye coordination. Read our post about the dangers of manganese fumes to learn more.

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

In Canada, the CNESST also adds these potential health risks to the list:

• 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

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

How to weld safely in a poorly ventilated area?

Basic questions

There are two aspects to this problem, and two obvious questions should be asked:

• Is the area poorly ventilated because it is impossible to get adequate ventilation? In many cases, the lack of ventilation is due to managerial decisions and could be corrected with some investments. Even in confined spaces, ventilation can be accomplished with a large hose attached to a fan on one end and lowered into a manhole on the other. The fan outside the confined space will blow out harmful gases and vapors, while fresh air should be drawn through an air intake.
• The second question is whether welding in this area is unavoidable. Maybe it would be possible to replace the welding operations with another process. Or to weld somewhere else.

Welding fume extractors are a must in poorly ventilated areas

The best way to protect welders and their colleagues from welding fume is by using fume extractors. For MIG welding, fume extraction MIG guns are the most efficient solution. They can be used with portable vacuum units or a vacuum system, giving excellent results. They can even be used in confined spaces.

An alternative would be 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 better. The only downside is that they cannot be used in most confined or cluttered spaces.

Finally, it is possible to use fume extraction nozzles. They are smaller and cheaper but require to be moved a lot while working as their efficiency area is limited. However, they are a viable alternative in confined spaces if fume extraction MIG guns cannot be used.

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

See our article How to Choose Fume Extraction Equipment for Confined Spaces? for more information.

Produce less toxic fume

The next step would be to see if the process could produce less toxic fume. An excellent way to do that is to evaluate different solutions with your engineers and suppliers. For example, you could make sure to remove all paint, lubricant, or solvent from the parts that will be welded. It is also worth considering changing the base and filler materials, shielding gas, wire, etc.

Personal protective equipment

Once all these solutions are in place, if you still do not meet the air quality standards, you will have to provide personal protective equipment to your welders. It 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 you will have to choose 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 to meet when welding in poorly ventilated areas

In the US, OSHA has established a Permissible Exposure Limit, or PEL, for welding fumes of 5 mg/m3. It is the weighted average concentration of the substance over 8 hours inside the welder’s breathing zone. Some 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. It will be necessary to analyze the components involved in the welding process to determine which substances must be monitored. Sampling the welding fume could also be required. It is also essential to know that OSHA does not tolerate 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 established its exposure limit, usually between 3 and 10 mg/m3. Some jurisdictions make a distinction between inhalable and respirable particles. In addition, 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

	TWA	STEL	C
AB	ALARA	ALARA	ALARA
BC	10mg/m3(i)* 3mg/m3(r)*	30mg/m3** 9mg/m3**	50mg/m3 15mg/m3
MB	10mg/m3(i)* 3 mg/m3(r)*	None	None
NB	10mg/m3(i)* 3mg/m3(r)*	None	None
NL	10mg/m3(i)* 3mg/m3(r)*	30mg/m3** 9mg/m3**	50mg/m3 15mg/m3
NT	5mg/m3	10mg/m3	None
NS	10mg/m3(i)* 3mg/m3(r)*	None	None
NU	5mg/m3	10mg/m3	None
ON	10mg/m3(i)* 3 mg/m3(r)*	30mg/m3** 9mg/m3**	50mg/m3 15mg/m3
PE	10mg/m3(i)* 3mg/m3(r)*	None	None
QC	5mg/m3	15mg/m3 **	25mg/m3
SK	5mg/m3	10mg/m3	None
YT	5mg/m3	5mg/m3	None

* Based on ACGIH recommendations.
** For 30 minutes during a workday.

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

Other dangers of welding in a poorly ventilated area

When welding fumes and other substances are not correctly extracted from a building, there is a chance to get an accumulation of gas, steam, or dust. This could cause a fire, deflagration, or explosion depending on the particles present in the air. Once again, air sampling might be necessary to evaluate the risk and take the appropriate measures to avoid an accident.