Welding generates a variety of hazardous substances, some of which can cause occupational asthma. Some operations can be even more hazardous.
Welding can sometimes be taken to include brazing and hard soldering processes but not usually soft soldering, which is completed at a much lower temperature.
The majority of welding fume comes from the filler rod, but the composition can vary significantly from that quoted in the material safety data sheet (MSDS) for the filler rod because of:
- the type of metal being welded;
- the welding process itself;
- the types of fluxes, filler rods and shielding gases;
- the parameters of the welding process (e.g. the electrical voltage in electric arc welding);
- the cleaning processes conducted immediately before welding (e.g. cleaning with a solvent);
- the types and quantities of dust in the air around the welding activity (e.g. from a fettling operation adjacent to the welding bay); and
- to some degree, the condition of the atmospheric air around the welding bay (e.g. humidity).
For this reason, it is very difficult to be certain what welding fumes contain, making a definitive risk assessment difficult. However, a risk assessment still needs to be completed. The services of a competent occupational hygienist will help make the risk assessment suitable and sufficient, as required by law.
Welding fumes are known to be hazardous, so welders and other employees likely to be exposed should be well protected from inhaling them. Employers should aim to remove as much welding fume as possible.
Assessing the risks
Risk assessments associated with welding and similar operations should recognise and appreciate the potential hazards, but you do not need to delve deep into the technicalities of fume contents etc. It is more important to establish suitable arrangements to minimise the risks to employees and others who may be affected (e.g. people who may be in the vicinity of the point where welding fumes are discharged into the atmosphere).
In the COSHH (ACoP) L5, paragraph 203(e), the HSE recognises the practical difficulties associated with effective management of welding fumes and states:
'203 The following are examples of circumstances where some or all air monitoring need not be carried out:
(e) where the exposure is to a mixture of substances, e.g. mixed solvents and welding fume. In these circumstances, it will be suitable as part of the regulation 6 assessment to measure all the components in the air, and then to select one or more ‘surrogate’ measurements such as total organics, or total fumes for air monitoring under regulation 10.'
Your competent occupational hygienist will be able to interpret this and define a simple ‘surrogate’ measure and a specification for a suitable control measure. Once the control measures are in place they need to be properly managed (see managing control measures).