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Metal Working Fluid - A Blog not to be Mist

On the 4th of May 2021, the Health and Safety Executive (HSE) began a campaign against occupational lung disease. Their main focus will be on businesses whose workers undertake welding and use metalworking fluids (MWF) to ensure that they are complying with the relevant guidance. It will be down to the duty holders to demonstrate they have suitable controls in place to protect the workers from occupational lung disease and an adequate occupational health risk assessment.


The HSE report that last year, 12,000 people died from lung diseases in the UK which were linked to past exposures at work. All welding fume has now been established to be capable of causing lung cancer, whilst metal working fluid has been found to cause occupational asthma and occupational hypersensitivity pneumonitis (OHP), amongst other lung disease.


The lung diseases mentioned above are debilitating and have life changing impact. We have covered them in more detail in this previous blog. We also covered welding fume, so be sure to check out that blog. However, we haven’t yet done anything on metal working fluid, so we thought we would give that a try!



What Does the Law Require


The Control of Substances Hazardous to Health (COSHH) Regulations, 2002 (as amended) require employers to carry out a risk assessment for those likely exposure to metal working fluids. This risk assessment should identify the controls required to ensure exposure is either prevented or adequately controlled. As metal working fluid can cause occupational asthma, adequate control requires reducing inhalation exposure as low as reasonably practicable (ALARP). As metalworking fluid can cause Dermatitis, skin contact must also be reduced. On top of these and as always, the COSHH principles of good practice given in 2A must be adhered to. Any inspections or checks on the control measures implemented must be recorded and retained for a minimum of 5 years.


It is also a requirement of the COSHH Regulations to provide a suitable program of health surveillance if there is a reasonable likelihood of a disease occurring in the workplace. As metal working fluid can cause Occupational Asthma and Dermatitis, the program would need to cover both skin and lung disease. The results of any health surveillance must be retained for a minimum of 40 years as required by the COSHH Regulations 2002 (as amended).


Controlling Exposure to Metal Working Fluid


When working with metal working fluid, there are many areas to consider such as storage, dilution from concentrate, maintenance of fluid, cleaning of the fluid systems and the subsequent safe disposal including emergency spillage procedures. To cover all these areas in full would turn this blog post into a thesis, so to keep things simple, we shall focus on controlling metal working fluid mist.


To effectively control metal working fluid to levels as low as reasonably practicable, engineering solutions need to be the priority. These include measures such as enclosing a machining process and implementing a time delay between the machine stopping and the opening of the doors. - this can be calculated using a smoke clearance test and should ideally be programmed into the specific machine. It should also be ensured that the metal working fluid delivery variables are accurately set to minimise mist production and to stop the fluid delivery as soon as the machining is completed.


Suitable local exhaust ventilation systems with an effective design and installation are instrumental to removing the metal working fluid mist from CNC enclosures. You will need to consult with a competent professional to ensure this is carried out effectively. The professional can also advise on the suitability of any recirculating filters (if applicable) and provide the initial commissioning test and the subsequent thorough examination and test (TExT) reports (also known as LEV examination and testing services). We have more information on LEV in this previous blog but to keep things brief, there is a legal obligation which requires all local exhaust ventilation systems to be thoroughly examined and tested at least every 14 months!

Maintaining and checking the performance of the local exhaust ventilation systems will ensure they continue to control exposure to metal working fluid mist. This is best achieved by an effective preventative inspection and maintenance programme. The operator should carry out regular checks which should be logged with any problems immediately reported. Airflow indicators can help the operator in easily carrying this out.


Compressed airlines are often used to blow down components to remove swarf and excess metal working fluid. However, this is actually a source of mist exposure and should be avoided wherever possible. Alternative methods should be considered such as enclosed component cleaning systems fitted with LEV, vacuum lines, absorbent materials, or degreasing/washing methods. If none of these are practical, then provide LEV for the use of compressed air, reduce the pressure to a level as low as practical for its purpose, or use longer lances or different nozzle designs.


Suitable information instruction and training should be provided on the health risks and associated symptoms associated with exposure to metal working fluid mist. Workers need to be fully aware of the controls in place to prevent or reduce exposure and know to report any suspected symptoms as soon as they become aware.


Last of all, we cannot forget personal protective equipment (PPE) and respiratory protective equipment (RPE). Suitable PPE includes work overalls, safety glasses and close-fitting easy-tear disposable gloves. The overalls should be laundered regularly, contaminated items should be removed immediately to reduce skin contact, and gloves may require to be thicker and provide chemical or mechanical protection when carrying out cleaning or maintenance. Whilst RPE isn’t typically needed during normal CNC machining, it may be required whilst carrying out mist generating cleaning procedures. In these situations, a minimum assigned protection factor of 20 is required. The PPE/RPE needs to be suitable for the task and wearer and be compatible with any other required equipment. PPE/RPE should also be stored and maintained, ideally in a dry clean cupboard. Check out our previous blog on 'RPE - Training, Maintenance, Storage and Disposal' for more information.


How we can help


At Blue Turtle Ltd, we provide a range of occupational hygiene monitoring services and can help you carry out your occupational health risk assessment. We can also help you to better understand your local exhaust ventilation systems and ensure you meet your legal obligations under the COSHH Regulations.


We help businesses of all types manage their workplace health hazards. Our experienced consultants can provide practical advice on how to achieve adequate control through process changes, improvements, or adopting/changing work practices to reduce the risk as low as reasonably practicable.


Whatever your Occupational Hygiene needs are, Blue Turtle Ltd is here to help your business protect your workforce and help you meet your legal obligations.


Give us a call today to discuss your needs or if you prefer, complete the online form with a brief outline of your business needs and/or concerns.


Blue Turtle - The missing cog in your business health!





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