top of page

Fundamentals of Welding Fume COSHH Risk Assessment

Understanding what comprehends suitable and sufficient COSHH Risk Assessment and how Occupational Hygienists evaluate the foreseeable risk associated with welding through evaluating COSHH.

In this article, we will provide an insight into how we as occupational hygiene professionals use our knowledge and experience to undertake suitable and sufficient COSHH Risk Assessments for specific welding processes, highlighting what needs to be considered.

In addition to this, we will also be explaining how the measurement of hazardous substances in conjunction with your COSHH Risk Assessment process can help determine foreseeable risk using qualitative and quantitative data. Showing the benefits of bringing a professional occupational hygienist into your business.

Lets Recap: Welding Fume Explained

Mixed particulate and gases are emitted by welding. The gas and particulate emission is dependant in the materials welded or the materials used to weld the metals together as fillers or fluxes. These can be inhaled and settle deep within the lungs causing both chronic and acute effects on health.

Common materials often welded are:

  • Mild Steel

  • High Nickel Alloy

  • Stainless Steel

  • Galvanised Steel

The consumables often used contain various metal fillers and fluxes which, individually pose a risk to health depending on what constituents are included in the products. Essentially, these form part of the overall fume.

Lets Recap: The HSE's Standpoint on Welding Fume

The Health and Safety Executive are currently focusing on businesses who utilise welding within their workplaces and enforcing against non-compliance with the COSHH Regulations. Rightly so as recent research has found welding fume to be carcinogenic. This is further to the known effects the likes of manganese and nickel have on the central nervous system, just one of many examples of how specific metal fumes can have a negative impact on target organs.

Back in February 2019, the Health and Safety Executive (HSE) published the document STSU1 2019 titled: Changes in Enforcement Expectations for Mild Steel Welding Fume. In this bulletin it is outlined that there has been new scientific evidence from the International Agency for Research on Cancer (IARC) that exposure to mild steel welding fume can cause lung cancer and possibly kidney cancer in humans and, as such, has been reclassified as Category 1: Carcinogenic to Humans.

Under this reclassification, the HSE have noted that regardless of duration, they will no longer accept any welding to be undertaken without any suitable exposure control measures in place. This is due to there being no known level of safe exposure.

Aspects to Look at to Form a Suitable and Sufficient COSHH Risk Assessment for Welding Activities

Who's Effected - Determining Who May Be Exposed?

Who's likely to be exposed here? Thinking beyond the worker is key to ensuring that other workers are not overlooked as part of the assessment. Fugitive emission (Fume which disperses into the atmosphere uncontrollably) may expose workers outside of the main welding process area. Office staff may also be affected.

The degree of fugitive emission, elevating the risk of exposure to"background" staff would be determined by evaluating the control systems in place, such as local exhaust ventilation, on-tool extraction, adequate segregation and containment and so on.

What Type of Welding is Undertaken?

We have provided a link to our Welding Processes article at the bottom of the page for further information. However, touching on the subject; it is fair to say that there are a number of variations in welding processes.

MAG/MIG, TIG, ARC, Submerged and so on. Each one is undertaken differently, using different materials, involving varied interaction from the operator.

What Materials Are Used, What Substances Are Emitted into the Workzone?

Suppliers of welding consumables should provide access to the Material Safety Data Sheets (MSDS), which can be used to determine a number of things. Such as:

The constituents mixed within the substance or materials present (the hazards).

The routes of exposure (Inhalation, Absorption, Ingestion, Injection).

The associated hazard and precautionary statements in line with the CLP Regulations.

  • Control and PPE Requirements

  • Firefighting Measures

  • First Aid Measures

  • Toxicological Data

  • Emergency Release Data

Regarding exposures, we would initially be concerned with what constituents make up the material, what the hazard statements are, what precautions should be taken and what controls are required.

What Controls Are In Place and Where Could Improvements be Made?

From a COSHH Risk Assessment perspective, the likelihood of exposure can be influenced by the suitability and efficiency of the current control systems.

Controlling welding fume should be at the forefront of any COSHH management process. That said, it is expected that exposures are controlled to as low as reasonably practicable, and businesses have a moral and legal obligation to ensure suitable and sufficient control of welding fume is achieved.

Control systems are implemented in line with the Hierarchy of control. To form part of the COSHH Risk Assessment it is key to understand the controls which are currently in place; using the following chart to help you.

With this information, we can determine how further controls can be implemented to achieve residual risk. Leading to maintaining levels as low as reasonably practicable.

Remember, the aim of controlling a substance hazardous to health is to protect the wider workforce as well as the individual process operator. Therefore, a full reliance on PPE/RPE is a failure to comply with the COSHH Regulations.

Although the Material Safety Data Sheets (MSDS) are not usually as in-depth as we would like, these are a good starting point in any substance risk assessment process. But to deliver a thorough assessment, it's important that we analyse details from the whole process. As professionals, we are trained to look for obvious signs of fugitive emissions and anticipate hazards which are possibly bypassing the control systems also using methods of quantifying exposures by measuring hazardous substances.

Measurement of Hazardous Substances

As mentioned in previous articles, the measurement of hazardous substances is key to ensuring real-time, accurate data is obtained from a process.

Workplace Air Monitoring / Exposure Assessments can be undertaken to determine airborne concentrations. The benefits of this type of assessment are that "actual exposures" can be measured over a desired time period. If done correctly, in line with the approved sampling methods set by the international the occupational hygiene standards representatives (HSE, NIOSH, OSHA and more), the quantification of exposure concentrations can help:

  • Test the effectiveness of current control measures

  • Map where exposures are likely to occur in higher concentrations

  • Determine a foreseeable risk

  • Address what substances are present in the air at a given time

  • Investigate and highlight poor use of control systems

A further method of determining and quantifying exposures is to undertake biological monitoring. Some substances have Biological Monitoring Guidance Values, outlined in EH40/2005. Essentially, exposures can be determined by taking samples of urine, blood, breath and more. The samples are analysed for metabolites which are present as a result of exposure to a particular substance.

Exposures are compared with Workplace Exposure Limits (WELs) set by the HSE in the EH40/2005 (As consolidated with the amendments 2020) in the UK. Although, international limits can be used if none are available in the EH40 document.

In our opinion, it is essential that exposures are measured.

How Do The Staff Behave? Do Staff Lack An In-Depth Understanding of the Hazards?

Extensive COSHH Risk Assessments should include information about behaviours. A qualitative assessment undertaken by watching and understanding how the chosen operator carries out the process is important. A lack of understanding around welding fume and its effects may lead to a poor perception of risk.

In addition to the above, the assessor needs to understand if Local Exhaust Ventilation is being used correctly, or if operators are cleaning their workpieces before welding for example. Small changes in a process due to increased understanding, will help workers understand their duties in contributing to reduced exposures in line with company policy.

By studying the process, occupational hygiene professionals can highlight a need to provide further information, instruction and training; working with the business to build a more substantial level of knowledge within the business.

What Health Surveillance Is In Place?

Implementing a suitable and sufficient Health Surveillance Program is key to ensuring workers are not suffering any ill health effects as a result of being exposed to hazardous substances. This is a necessity and forms part of the COSHH Regulations (Regulation 11).

From a COSHH Risk Assessment perspective, it is key to highlight a need to undertake specific health surveillance. With regards to welding, lung function testing and skin assessments would be required.

To Summarise:

A COSHH Risk Assessment for welding fume can be complicated for people who are inexperienced. It is always recommended that a company employs a competent person to undertake a COSHH Risk Assessment so that foreseeable risk can be determined accurately based on experience and knowledge.

A professional occupational exposure assessment can also be undertaken to support the COSHH Risk Assessment, enabling levels of exposure to be determined using actual data representative of the processes measured. The benefits of this approach can be found in our article below.

Do You Need Support with COSHH?

It is hoped that this article goes some way to providing a brief overview of COSHH. If you wish to know more on this subject or need support with your COSHH assessments, exposure monitoring or the testing of your LEV systems, RPE Fit Testing then please feel free to get in touch with us through social media or our website (, by email at or simply give us a call on 01709 931299.

Visit our Services Page Here:

1,120 views0 comments


bottom of page