Studies suggest that exposure to manganese, present in mild steel welding fume, can lead to neurological symptoms similar to Parkinson’s disease. These symptoms include speech and balance disorders. There are new studies underway in this area that will help HSE decide whether more action is needed.
The respirable manganese WEL of 0.05mg/m3 (8hr TWA) is appropriate because much of the manganese in the fume will be small particles that reach the deep lung (known as respirable particles).
When the manganese fume particles are breathed in routinely over a period of time they cause a systemic effect. This means the manganese can be absorbed into the body through many routes and can cause neurological effects.
It is highly likely that the respirable manganese WEL will be exceeded during many welding activities unless effective controls are introduced and used properly. You could carry out exposure monitoring to see if you are complying with the WEL.
Welding and hot cutting processes do not usually generate harmful levels of vibration. But there may be a risk from some associated tasks like grinding, needle scaling etc. For more information and HSE’s ‘vibration exposure calculator’ go to the HSE hand-arm vibration pages.
With the exception of TIG, electric arc welding generates harmful levels of noise. The process itself produces noise, the other tasks that a welder will typically do are also noisy, and welding is generally carried out in a noisy environment. Noise levels experienced during arc welding and cutting vary with the process. The table gives typical noise levels for different types of welding process and associated tasks.
||Typical noise levels
||up to 75 dB(A)
|Plasma cutting (hand-held up to 100 A, cutting up to 25 mm thickness only)
||up to 100 dB(A)(typically above 90 dB(A) when cutting thicknesses above 40 mm)
|Air arc gouging
The actual noise levels will depend on several factors. For instance, noise is likely to increase with increasing consumable diameter and with increasing current. Also, the type of metal being worked will have an effect. Stainless steel tends to produce higher noise levels than mild steel.
Where cutting is concerned, the thickness of material being cut will affect the noise produced, thicker materials being noisier.
For the loudest processes (plasma cutting and air arc gouging) the dominant source of noise is the high-pressure compressed air. The design of air nozzle can have a big effect on noise emission and some companies may offer ‘reduced noise’ equipment.
Typical noise exposure
Daily personal noise exposure depends both on the level of noise (the dB(A) value) and the time of exposure during a working day. When assessing potential noise exposure, it is important to consider how long welding operations last. For welding and hot cutting processes, noise is only generated when an arc is struck or flame lit. A production welder’s ‘arcing’ time may be as much as 80% of the shift. A fabricator welder may spend most of the day setting the job up before starting any welding. Sometimes setting up can be fairly quiet, for example marking out. At other times it can be quite noisy, for example edge preparation by manual grinding.
Welders also often work in noisy environments and carry out other noisy operations, such as needle scaling and grinding. It is likely that a welder’s individual noise exposure will be affected not only by their own work, but also by the work of their colleagues.
You should consider these factors when assessing noise risk. Underestimating noise risk could lead to damaged hearing. But over-estimating noise exposure could lead to unnecessary expense or overprotection.
Employers should eliminate the noisy process where possible, perhaps by buying in the material cut to size by the supplier. But welding and hot cutting is often the only practical method, so the main focus should be on:
- using practical methods to reduce noise levels for the given process
- managing the residual risk using ear plugs, ear muffs or other hearing protection
An example of this would be moving from hand-held plasma cutting to an automated submerged plasma cutter. This can keep noise levels below 80 dB(A). Water-shrouded plasma cutters are available and may be practical for some operations. Submerged or water-shrouded systems reduce fume emission as well as noise. With any alternative ways of working, weigh the practicality of the alternative and investment required against the benefits (health, safety, productivity, etc):
- As a general rule, noise from arc welding increases with wire/rod diameter and operating current. Using a wire/rod size and current appropriate for the job and not excessively large should help to minimise noise levels
- With plasma/flame cutting and arc gouging, noise levels generally increase with increasing gas velocity. Ensuring that the gas velocity is as low as possible (for example reducing the outlet pressure at the regulator) will generally reduce the noise levels. There is a trade-off between productivity rate and gas pressure. But there will be a crossover where increased gas pressure does not significantly increase productivity
- Welding in confined spaces or other areas where sound may be reflected (such as the corner of a workshop) can give higher noise levels than if the welding is carried out in an open space. If it is not possible to organise the work to avoid these situations, adding sound-absorbing materials to the reflective surfaces can help reduce the impact of the welding noise on other people working nearby
Hearing protection selection should be based on 4 criteria:
- its ability to reduce noise exposure
- its compatibility with other PPE (welding masks, safety helmets etc)
- suitability for the working environment and activity
Ear plugs and slimline ear muffs with a neckband rather than a headband may be more compatible with welding masks.
If hearing protection is used as the main control in reducing noise exposure, workers should be trained in its use. Workers should wear the protection all the time they are in a noisy area, or doing noisy work. Hearing protection becomes significantly less effective if workers do not use it for even a small amount of the time they are exposed.
There is more information on HSE’s noise and vibration web pages.