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Minimising Exposure to Welding Fume

Introduction

In February 2019, the Health and Safety Executive (HSE) in the UK issued a new Safety Alert related to the fume from welding mild steel as a potential cause of cancer. This alert follows a review of scientific evidence from the International Agency for Research on Cancer (IARC) that determined that exposure to welding fume can cause lung cancer and possibly kidney cancer in humans. In IARC Monograph 118, the classification of welding fume was changed from “possibly (Group 2B) to “definitely” (Group 1) a carcinogen. As a result, new requirements for the control of welding fume have been introduced in the UK. Essentially, the exposure to fume from welding all metal alloys should now be controlled in the same way as for stainless steels.

Workplace Exposure Limits

Workplace exposure limits (WELs) for the constituents of welding fume are provided in HSE Publication EH40. Generally, these limits are for exposure averaged over 8 hours, although for some components the average time is 15 minutes.  In the UK there is no WEL for total welding fume, so exposure to each constituent needs to be considered.  Welding fume is generally considered to be particulates varying in size from less than 1µm to over 20µm. Depending on the welding process, most of the particles are in the respirable fraction, which is  less than 10µm. There are also gases in welding fume which are hazardous to human health. Specifically, nitrous oxides (NOx), carbon monoxide and ozone have WELs, and new limits were introduced for carbon monoxide, nitrogen monoxide and nitrogen dioxide in 2018. New limits were also introduced for manganese compounds, see Table 1.

Of particular concern are the oxides of nickel and hexavalent chromium, which are carcinogens and manganese, which has a neurological effect similar to Parkinson’s decease.

Table 1. Workplace exposure limits in the UK for the main components of welding fume   (Ref EH40:  Third Edition 2018)
Table 1. Workplace exposure limits in the UK for the main components of welding fume (Ref EH40: Third Edition 2018)

Factors Affecting Welding Fume Emissions

Particulate welding fume originates primarily from the welding consumable as vapour from the molten droplet. Substances with a high vapour pressure and low vaporization temperature transfer into the fume more readily than other constituents, so, for example, manganese transfer is high but chromium and nickel transfer is low. Therefore, welding consumable composition cannot be taken as a guide to fume composition. The best way to reduce welding fume exposure is to reduce the quantity of fume at source. Welding parameters, particularly pulse and other waveform control technologies, may reduce fume emission rates and shielding gas also plays a role. Welding consumable manufacturers are also developing products that emit lower levels of fume and are formulated to reduce specific constituents such as hexavalent chromium.

UK HSE Requirements

The IARC conclusions have created a change in the HSE enforcement expectations for exposure to welding fume, whereby all businesses undertaking welding activities should ensure effective engineering controls are in place and correctly used to manage fume. The HSE have stated that general ventilation does not achieve the necessary air quality and that suitable controls, such as Local Exhaust Ventilation (LEV), should be used. LEV can be difficult to use effectively when welding large components, so the use of on-torch extraction should be considered.

The HSE Safety alert states:

  1. Make sure exposure to any welding fume released is adequately controlled using engineering controls (typically LEV).
  2. Make sure suitable controls are provided for all welding activities, irrelevant of duration.  This includes welding outdoors.
  3. Where engineering controls alone cannot control exposure, then adequate and suitable RPE should be provided to control risk from any residual fume.
  4. Make sure all engineering controls are correctly used, suitably maintained and are subject to thorough examination and test where required.
  5. Make sure any RPE is subject to an RPE  programme[1]. An RPE programme encapsulates all the elements of RPE use you need to ensure that your RPE is effective in protecting the wearer.

Welders must be suitably instructed and trained in the use of any controls, which should be used irrespective of the duration of the welding as there is no known level of safe exposure. Risk assessments should also be carried out to reflect these new control measures.

If the exposure monitoring data shows control to below the relevant WELs (e.g. chromium, nickel, manganese, etc.) then no further action is required.

 

Avatar Geoff Melton Technology Manager - Arc Processes and Welding Engineering

Geoff Melton is a Technology Manager at  TWI in the UK  and is the Chairman of IIW commission VIII, 'Health, Safety and the Environment.' Since graduating from the University of St Andrews in Scotland with a degree in Physics and Electronics, he has worked in welding research and development for nearly 40 years. As well as chairing IIW commission VIII he is also the chair of CENELEC TC26 on electric welding equipment. Geoff was the first convenor of a working group set up between IEC and ISO to write a new series of international standards for arc welding equipment ( IEC 60974). This lead to developing standards for electromagnetic compatibility ( EMC) and the health effects of exposure to electromagnetic fields (EMF) in welding.  At TWI, he leads a wide portfolio of research projects from welding fume to  automated welding process developments  for low/zero  emissions automotive applications. Geoff also has a MBA from Loughborough University and is a Chartered Engineer  and Chartered Physicist.

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