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Health, safety and accident prevention - control of welding fume


Exposure to fume


For many gas and arc welding processes, the fume concentration in the immediate vicinity of the weld is well above its exposure limit. The amount of fume generated is determined primarily by welding process, consumable and welding procedure. However, the following aspects are likely to influence the degree to which the welder is exposed to fume:

  • welding position
  • location and type of workplace
  • exposure duration

Thus, welders using the same process may be exposed to different levels of fume. The risks for each job should, therefore, be assessed individually.

Welding position

The welding position (flat, vertical, horizontal or overhead) and proximity of the welder to the fume plume affect exposure. As the welder naturally bends over the workpiece, the flat position induces the highest level of fume in the breathing zone. The welder should adopt a working position which ensures that his head is away from the plume.

Location and type of workplace

Welding in a large workshop, or outdoors, prevents build-up of fume and gases. However, in a small workshop, fume will not be readily dispersed and the welder may be subjected to a higher than average exposure. Working in confined spaces, in particular, requires an efficient, monitored, ventilation system so exposure is controlled and there is no depletion of oxygen in the working atmosphere.

Exposure duration

The long-term occupational exposure limit (OEL) given in Job Knowledge for Welders No. 31 relates to the average concentration over an eight-hour period. Exposure will be intermittent, mainly during the arcing period. There should be relatively little exposure between arcing periods but this may be influenced by the presence of other welders, effectiveness of control measures and general ventilation. Furthermore, as work patterns (arcing time and down time) vary from day to day, average exposure may often only be assessed by frequent sampling.

Control of welding fume

If welding fume cannot be eliminated, control measures should be adopted as follows:

  • choice or modification of the welding process
  • improvement in working practices
  • ventilation
  • use of respiratory protection equipment (RPE)

RPE should not be considered until the effectiveness of all other techniques has been explored.

Choice or modification of the welding process

Process choice is usually made on the basis of weld quality, economics and equipment availability. Nevertheless, if other processes can be used, it should be borne in mind that some processes, such as submerged-arc and TIG, generates significantly less particulate fume than MMA, MIG and FCAW. Consumable manufacturers also supply information on fume composition which can be used in selecting welding rods for a particular job.

Improvement in working practices

A substantial improvement can often be made by placing the workpiece so the welder can avoid the plume which rises above the weld.

In large scale fabrications, the welding sequence should be organised to minimise the work carried out in enclosed or confined spaces.

Safe practice and accident avoidance

  • adopt position and techniques to keep head out of welding plume
  • avoid welding in enclosed and confined spaces


Strategy for using ventilation to control fume

The strategy for using ventilation to control fume is shown above.

The most efficient way of controlling exposure to welding fume is its removal at source. There are several methods of removing fume close to the weld:

Extracted benches
Extracted benches
Extracted booth
Extracted booth
Local exhaust ventilation (LEV)
Local exhaust ventilation (LEV)
On-gun extraction
On-gun extraction

As local exhaust ventilation (LEV) and on-gun extraction systems are never 100% efficient, especially when welding awkward structures, general ventilation may also be necessary to control the background level of fume.

As each type of extraction equipment has limitations, it is important to select the right equipment for each job. It is also essential that welders are adequately trained to use the equipment and adopt good working practices. Supervision is needed to ensure the equipment is being used effectively and to minimise background fume level in the workshop.

Safe practice and accident avoidance

  • check that the equipment is working correctly and is regularly maintained, for example, cleaning and replacing filters according to manufacturer's recommendations
  • place the extraction hood or nozzle to capture the fume without disturbing the gas shield
  • when welding large structures, reposition the hood at appropriate intervals to ensure fume continues to be effectively extracted

Respiratory protection equipment (RPE)

Where fume needs to be controlled, LEV should always be used to achieve as much control as possible. If LEV is not possible, or there is still unacceptable exposure, RPE is needed. RPE should always be the least preferred means of control because it only protects the wearer. Other methods are all aimed at preventing exposure whereas RPE is essentially curative. There are two types of RPE:

  • respirators - workshop air cleaned before being inhaled
  • air-supplied - air supply is separate from workshop atmosphere

Selection of suitable RPE will require the advice of an expert who can make the selection based on fume concentration, presence of toxic gases and whether there is a oxygen deficient atmosphere.

Safe practice and accident avoidance

  • Consult expert in choice of respirator
  • Each welder to be personally fitted with an RPE to ensure that it provides adequate protection
  • Personnel to be trained in use of an RPE and its maintenance and cleaning
  • Management to ensure systems exist for control of equipment and training

Publications and relevant standards

HSE HS(G)202
General ventilation in the workplace, HSE Books.
An Introduction to Local Exhaust Ventilation, HSE Books
Respiratory Protective Equipment - a Practical Guide, HSE Books.

The article was prepared by Bill Lucas and Geoff Melton, TWI, in collaboration with Roger Sykes, Health & Safety Executive.

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