Controlling exposure to welding fumes
Information for employers and employees on controlling exposure to welding fumes.
Purpose of this guidance
In March 2017, the International Agency for Research on Cancer (IARC) re-classified welding fumes from a Group 2B carcinogen (possibly carcinogenic to humans) to a Group 1 carcinogen (carcinogenic to humans).
The purpose of this document is to:
- Increase awareness of the risk associated with exposure to welding fumes
- Provide guidance on controlling the risk from exposure to welding fumes
Main types of welding processes
There are many different types of welding processes, the most widely used is arc welding. Arc welding is a process where two metal parts are joined together by melting them at very high temperatures and allowing them to cool and fuse together.
The four main arc welding processes (in decreasing order of fume generation) are as follows:
- Flux Cored Arc Welding (FCAW)
This process uses a continuous feed filler metal with a hollow core filled with flux that generates a shielding gas and slag to protect the weld. An external supply of shielding gas from a gas cylinder may also be required where some FCAW consumables generate minimal shielding. Self-shielded FCAW, in particular, can generate very high levels of fume.
- Manual Metal Arc Welding (MMAW)
This process is also known as Shielded Metal Act Welding (SMAW), stick welding, manual welding or manual metal arc welding. The electrode is a consumable metal coated with a flux, which as it breaks down generates carbon dioxide (CO2), and in some cases fluorides, that shields the weld (i.e. reduces oxidation of the metal) and forms a slag.
- Gas Metal Arc Welding (GMAW)
This process uses a spool of continuously fed solid wire electrode (bare metal or copper coated wire) and an external supply of shielding gas (e.g. Argon & CO2). It is widely used in industry and commonly referred to as MIG (metal inert gas) welding. The dip transfer method generates less fumes than the spray transfer method.
- Gas Tungsten Arc Welding (GTAW)
This process is also known as Tungsten Inert Gas Welding (TIG). This process uses a non-consumable tungsten electrode. The filler metal is added manually using a separate rod usually of similar composition to the base metal. TIG welding is used for pressure equipment welding, welding stainless steel, aluminium and other non-ferrous metals. Argon and helium are typically used as shielding gases.
Widely used in industry
These processes are widely used in industry to weld various metals, including mild and high tensile steel, low and high alloy steels, stainless steel, aluminium, galvanised steel and various alloys. They generate fumes containing a mixture of very fine particulates and gases including ozone.
Welding fumes composition
The composition and concentration of the welding fumes depend on the following:
- the welding process and power settings used, for example: voltage, current, mode/polarity
- the base metal being welded, for example: mild steel, alloy steel, stainless steel, galvanised steel, aluminium
- composition of the welding rod/electrode or filler metal wire
- shielding gases or flux used
- contaminants or coatings present on the metal being welded, for example: solvents, paints, oil, chromium, zinc, etc
Information on the composition of the various metals, alloys welded and the welding rods, electrodes and fluxes used is readily available. This information can be used to predict the major components of welding fumes that may be present or of concern.
Main welding fumes composition from metals welded
- Mild and high tensile steel
- iron oxide, fluoride
- manganese
- ozone
- copper - if copper coated filler wire used
- Low and high alloy steel
- iron oxide, fluoride
- manganese, fluoride, nickel, chromium, ozone
- copper - if copper coated filler wire used
- Stainless steel
- chromium, nickel, copper
- ozone, nitrogen oxides
- Hardfacing
- chromium, nickel, copper, cobalt, fluoride, tungsten
- ozone, nitrogen oxides
- Aluminium
- aluminium oxide, ozone, nitrogen oxides
- Galvanised steel
- zinc oxide
- Beryllium copper alloys
- beryllium, copper
This information is useful in determining the potential health effects, atmospheric monitoring and health surveillance for an employee.
Health effects of welding fumes
Exposure to welding fumes is known to cause short and long-term health effects.
The short-term health effects may include:
- irritation of the eyes and mucous membranes
- respiratory irritation
- metal fume fever (zinc oxide)
The long-term effects may include:
- siderosis
- lung and kidney cancer
- effects on the nervous system
- asthma
- pre-disposition to pneumonia
The risk to a welders' health depends on the composition of the welding fume and their level of exposure. This is determined by:
- the composition and concentration of the welding fumes generated by the type of welding process used (see previous section)
- the duration and frequency of exposure (the arc time or the actual time spent welding)
- welders' posture and head position relative to the welding fume
- location of the welding process, for example: indoors, outdoors, restricted or confined spaces
- the type of controls in place to prevent or reduce exposure to fumes, and their effectiveness
How to control exposure to welding fumes
Under the Occupational Health and Safety Regulations, 2017 (OHS Regs), Part 4.1 - Hazardous Substances, employers are required to control risks in accordance with the hierarchy of control (refer to the OHS Legislation section below).
A simplified method or approach of implementing the hierarchy for controlling welding fumes exposure is to minimise the level of fume by focusing on the process first, followed by ventilation and then respiratory protection if exposure is still excessive. The table below is a summary of this approach.
- Process controls
- eliminating welding process
- substituting process
- process modification
- process set-up and preparation
- Ventilation controls
- on-tool extraction
- local exhaust ventilation (extraction)
- dilution ventilation (fan)
- Respiratory Protective Equipment (RPE)
- powered air purifying respirators (PAPR)
- half-face cartridge respirator
- P2 disposable respirator
Often a combination of control measures is required to effectively control risks to health and safety from exposure to welding fumes. This is particularly the case where there is extensive welding of large structures taking place, which requires employees to move around and weld in different positions. The various control measure are described in detail below:
Process controls
Eliminating welding process
Consider using other processes to eliminate or reduce the need to weld, for example:
- use other fastening processes, such as nuts and bolts
- purchase pre-fabricated components
Substituting process
Where elimination is not possible, consider adopting alternative processes, such as:
- using a welding method that generates less welding fumes, such as TIG welding or GMAW (MIG) instead of MMAW or FCAW
- using pulse transfer GMAW instead of spray transfer to reduce fume levels
- using automation or robotics to weld materials
Modification of the process
Consider modifications to the welding settings and gases used that reduce the level and type of fumes generated such as:
- reducing the current in MIG welding to reduce the fumes generated
- using waveform controlled processes in MIG welding to reduce the fumes generated
- changing the shielding gas, flux or electrode used to reduce and alter the composition of the fumes generated
- using Argon rich shielding gas instead of CO2 and helium rich mixtures in GMAW reduces the level of welding fume generated
Process set up and preparation
- redesigning the workstation or reposition the workpiece being welded to a suitable height using a stand or jib so that the welder is not leaning right over the fumes
- cleaning the parts to be welded or remove surface coatings prior to welding
- relocating employees who are not involved in welding to avoid unnecessary exposure
Ventilation controls
This section provides an overview of:
- the different types of ventilation available that may be used to reduce exposure to welding fumes
- the advantages and disadvantages of each method
- how they may be utilised in the workplace
The following ventilation controls are presented in order of effectiveness in controlling welding fumes.
On-torch extraction systems are designed to capture the fumes at the source without affecting the shield gas. Current torch designs are slimmer, lighter and easier to handle.
On-torch extraction is effective where there is extensive, highly variable, customised metal fabrication of larger structures. It is effective in situations when flexible local exhaust ventilation is not very practicable or it requires the welder to constantly correctly re-position the hood.
The effectiveness of on torch extraction can be impacted when working on overhead or vertical surfaces.
This is an example of an on-tool capturing hood where fumes are extracted into the vents at the sides of the torch handpiece.
Image credit: WorkSafe New Zealand
Mechanical LEV is suitable for situations where the welding is repetitive and the objects or structures being welded are small to medium in size which will fit within the extraction range
Suitable Mechanical LEV may include the following:
- fixed system such as a downdraft table or side draft booth
- fixed or portable flexible extraction hood
This is an example of mechanical local exhaust ventilation where the welding fumes are extracted downwards, or to the back of the bench, away from the welder.
Image credit: WorkSafe New Zealand
Flexible LEV is generally suited to the welding of smaller structures or workpieces that only require limited movement of the hood. It can be inconsistent or unreliable where it needs to be frequently moved and correctly positioned so as to capture the fumes without affecting the shielding gas.
The shape and size of the hood also needs to be suitable for the job. For example, a wider rectangular hood may be more suitable for long straight welds than a round hood.
This is an example of flexible local exhaust ventilation where the capturing hood has a long flexible flue that enables it to be positioned where the welding is taking place.
Image credit: WorkSafe New Zealand
Used alone or in combination with general extraction systems (i.e. push pull), fans can be effective in dispersing or diluting welding fumes. Fans should only be used as the sole means to disperse the fumes in limited circumstances, as fans can spread fumes throughout the workplace. It is not a recommended method where the fans blow the fumes to other workers in the vicinity.
Fans need to be positioned to the side of the welder and not directly behind them because the flow can draw the fumes into the welder's breathing zone. Positioning fans too close to the welder can also affect the shielding gas.
Position fans to create a cross-draught
This diagram shows how fans positioned on the left or right of the welder create a cross-draught that moves the fumes away from the welder – while fans positioned behind or in front of the welder may cause the welder to inhale more fumes.
Natural ventilation, such as working in a large open area or near a large open doorway with a good cross draft, may be sufficient in limited circumstances to dilute and prevent the significant build-up of fumes within the workplace. However, it is important to note that natural dilution ventilation is often unreliable and inconsistent and cannot be relied on particularly where high levels of welding fumes are present.
Respiratory Protective Equipment (RPE)
Respirators are a type of personal protective equipment (PPE) which is the lowest level in the hierarchy of control.
RPE is generally the least effective control measure and should only be relied on:
- where higher level control measures are not practicable
- to supplement other control measures
- as an interim measure until higher level controls are implemented
RPE, including highly effective powered air purifying respirators (PAPR), can protect the person wearing the respirator but they do not control the fumes at the source. When they are used as the only control measure they do not prevent the build-up of fumes where there is extensive welding. This can result in secondary exposure of welders and other persons in the vicinity of the welding fumes.
Respirators must comply with Australian standard (AS/NZS 1716:2012 Respiratory Protective Devices) or its equivalent, and should not be shared among welders.
The type of respirator required or suitable will depend on a range of circumstances, including the concentration of fumes, the duration of the welding task and the effectiveness of any other controls being used, such as ventilation. Note that PAPR provides the highest level of protection in comparison to the half face cartridge respirator and the half face disposable respirator.
Employers should ensure that their employees are provided with instruction, information and training to ensure RPE is properly used, fitted, and maintained. The types of RPE that may be suitable for welding in order of effectiveness include:
Powered air purifying respirators (PAPR)
PAPR's are available as part of a welding shield or helmet. They provide flexibility to allow welding in many different positions and provide a high level of protection and do not rely on a facial fit such as disposable or cartridge respirators.
PAPR's can be effective where LEV is not practicable or effective and where there is extensive and highly variable welding of larger structures. PAPR's can also be much more comfortable than the other respirators and the cartridges last longer as they are larger. The air is drawn from the side or the rear of the operator through a filter instead of from within the welding plume.
Half-face cartridge respirators
Half-face non-disposable respirators fitted with P2 or P3 cartridges can be suitable for welding fumes if they can be worn under welding face-shields.
Cartridges also containing charcoal are effective in controlling employees’ exposure to ozone, which is broken down to oxygen when it comes in contact with charcoal.
When using a half-face non-disposable respirator, the wearer needs to be clean shaven to ensure a good facial seal.
Half-face disposable respirators
P2 disposable respirators are designed for thermally generated fine particulates generated by welding processes. P1 disposable respirators that are designed for larger mechanically generated particles are not suitable for welding fumes.
Charcoal-infused disposable respirators are also effective in controlling employees’ exposure to ozone which is broken down to oxygen when it comes in contact with the charcoal.
When using a P2 disposable respirator, the wearer needs to be clean shaven to ensure a good facial seal.
Welding in confined spaces
Welding in confined spaces can expose employees to high levels of welding fumes. While exposure to welding fumes is a concern in confined spaces, of greater concern is the potential for shielding gases supplied by an external source, such as a gas cylinder, to displace the oxygen in the space and cause asphyxiation. The likelihood of this depends on the flow rate of shielding gas, the duration of the welding process, the size of the space and level of ventilation in the space.
Welding in confined spaces can require the use of a combination of controls, including mechanical extraction ventilation, monitoring oxygen concentrations and the use of effective respiratory protection, such as PAPR or air-supplied respirators, to ensure that there is a safe level of oxygen, and employees are not exposed to welding fumes beyond the exposure standard.
For further guidance on work in confined spaces, refer to:
- Part 3.4 of the Occupational Health and Safety Regulations, 2017
- Confined spaces guidance
Employees welding in a restricted space, such as a small space with poor ventilation which does not meet the definition of a confined space can also be exposed to high levels of welding fumes.
Exposure standards for welding fumes
Occupational or workplace exposure standards are airborne concentrations of a particular substance or mixture of substances which must not be exceeded. There are three types of exposure standards:
- 8-hour time-weighted average (TWA)
- Short term exposure limit (STEL) - average airborne concentration over a 15-minute period
- Peak limitation (Pk) - a maximum or peak airborne concentration of a substance determined over the shortest analytically practicable period
Exposure standards represent airborne concentrations of individual substances which, according to current knowledge, should not cause adverse health effects nor cause undue discomfort to nearly all workers.
Workplace exposure standards for airborne contaminants are listed on the Safe Work Australia website and its Hazardous Chemical Information System (HCIS)
Exposure standards for typical components of welding fumes
This table lists the main welding components of welding fumes and relevant exposure standards at time of publishing:
Components (Click to sort descending) | 8hr TWA (Click to clear sorting) | STEL (Click to clear sorting) | Peak (Click to clear sorting) |
|---|---|---|---|
Aluminium oxide | 5mg/m3 | ||
Beryllium | 0.002mg/m3 | ||
Cadmium | 0.01mg/m3 | ||
Chromium (III) compounds | 0.5mg/m3 | ||
Chromium (IV) compounds | 0.05mg/m3 | ||
Copper | 0.2mg/m3 | ||
Iron oxide | 5mg/m3 | ||
Lead | 0.5mg/m3 | ||
Manganese | 1mg/m3 | ||
Nickel (soluble compounds) | 1mg/m3 | ||
Nitrogen dioxide | 0.3ppm | ||
Ozone | 0.1ppm | ||
Phosgene | 0.02ppm | 0.06ppm | |
Welding fumes (not otherwise specified) | 1mg/m3 | ||
Zinc oxide | 5 mg/m3 |
It is important to note that even if the exposure standard for welding fumes (not otherwise specified) has not been exceeded, an employees' exposure to specific components of the fumes may exceed the exposure standard for that particular substance present in the welding fume. In any event, an employees' exposure to welding fumes should always be minimised irrespective of the exposure standard limits.
Atmospheric monitoring
Employers must ensure that atmospheric monitoring (reg 166) is carried out in relation to a hazardous substance generated at the workplace if there is an exposure standard for the hazardous substance or its ingredients and;
- there is uncertainty, based on reasonable grounds, whether the exposure standard may be exceeded, or
- where it is necessary to determine if there is a risk to health
If it is reasonably likely (based on the level of welding fumes observed and the duration of exposure) that employees exposure to welding fumes is not likely to exceed the exposure standard(s), then atmospheric monitoring would not be required. Similarly, if it is obvious that exposure is above the relevant exposure standard(s), then employers must control the risk in accordance with the hierarchy of control.
Uncertainty to whether an exposure standard(s) may be exceeded can occur when the nature of the welding work is highly variable and intermittent. In such cases, the options for an employer would be to conduct air monitoring and/or implement effective controls that remove the uncertainty.
Atmospheric monitoring can include both personal and static air monitoring. Only personal air monitoring can be directly compared to the exposure standards.
Personal air monitoring should be conducted inside the face shield by a competent person with the requisite skills and knowledge, such as an occupational hygienist, in accordance with relevant and recognised or approved methods. Details including the type of welding process, the controls in place and the duration and frequency of exposure also need to be recorded to assist in the interpretation of the results and comparison with relevant exposure standards.
Static air monitoring may be useful in determining the concentration of welding fumes in a particular area or nearby areas where other people may be working.
Personal air monitoring may provide useful data
Personal air monitoring needs to be conducted within the welders face shield. A pump that draws air through the sampling filter is worn on the hip.
Health monitoring
Employers must ensure that health monitoring is carried out for an employee if:
- they are exposed to substances listed in Schedule 9 of the OHS Regulations and
- the exposure is reasonably likely to have an adverse effect on the employee’s health under the particular conditions of work at the workplace
This may be the case where there is heavy reliance on low order controls such as respiratory protective equipment or administrative controls to control excessive exposure below relevant exposure standards.
The relevant substances present in welding fumes that are listed in Schedule 9 are inorganic compounds of cadmium, chromium and lead. To assist employers to comply with this duty, employers need to determine whether these substances are present in the welding fumes and whether they are likely to be present in sufficient concentrations to have an adverse health effect on employees.
Employers should consult or obtain advice from a medical practitioner or occupational physician on suitable health monitoring for exposure to welding fumes.
Guidance on suitable health monitoring for the specific compounds is available from SafeWork Australia.
OHS Legislation
Under the OHS Act, an employer must, so far as reasonably practicable, provide and maintain a working environment that is safe and without risks to health. This requires an employer to eliminate the risks to health so far as reasonably practicable and if it is not practicable to eliminate the risk, then to reduce the risks so far as is reasonably practicable.
In addition, employers must:
- Consult with employees and their Health and Safety Representatives in relation to a range of matters, such as the identification of hazards and risks at the workplace, making decisions about the measures taken to control risks, and making decisions about the procedures for things such as monitoring the health of employees and conditions at the workplace (such as through atmospheric monitoring), and providing information, instruction and training to employees
- Provide supervision and information, instruction and training as is necessary to allow employees perform their work in a way that is safe and without risks to health. Information, instruction and training should outline the hazards and risks associated with the welding processes used at the workplace, and provide instructions to employees on the control measures implemented at the workplace
Part 4.1 of the OHS Regulations 2017 on Hazardous Substances, imposes specific duties in relation to an employee exposure to hazardous substances including:
- Controlling risks according to the hierarchy of control (Regulation 163):
- Elimination
- Substitution
- Engineering / Isolation
- Administrative
- Personal Protective Equipment (PPE)
- Ensuring that the exposure standard is not exceeded (Regulation 165)
- Undertaking atmospheric monitoring and health monitoring in certain circumstances (Regulations 166 and 169)
- Record keeping obligations regarding the results of air monitoring and health monitoring (Regulation 168 and 171)
- Reviewing control measures regularly (Regulation 164)
In addition, in accordance with Regulation 18, employers must ensure control measures are properly installed, used and maintained.
Most major manufacturers and/or suppliers of metals and welding consumables will typically produce and supply safety data sheets (SDSs) for their products upon request. Whilst these materials are generally not classified as hazardous under the Regulations, the fumes generated during welding present a risk to health, hence manufacturers or supplies do have a general duty under the OHS Act to provide adequate information to ensure the safe use of their products.
Employers should obtain information about the welding products to allow them to predict the composition and concentration of the welding fumes generated, and assist them in determining appropriate controls.