Health and Safety for Metalworking Fluids (MWFs)

Metalworking fluids (MWFs), often referred to as coolants, play a vital role in machining by reducing heat and friction. However, they can also introduce significant health and safety risks if they are poorly controlled. Long-term exposure to MWF mist, aerosols, and contaminated fluid can contribute to serious ill-health, including respiratory conditions, dermatitis, and other chronic outcomes. A strong risk assessment process under the HSE COSHH framework helps identify where exposure can occur and what control measures are needed to protect workers.

This page outlines practical controls and best-practice steps to help reduce risk from MWFs in workshops, production lines, and maintenance environments, alongside links to additional Serpro resources and recognised external guidance.

Why MWFs need careful control

MWFs can present hazards through inhalation (mist/aerosols), skin contact (splashes, contaminated surfaces, soaked gloves), and secondary exposure from poor housekeeping. Risks can increase when fluids degrade, become contaminated, or are used in high-pressure operations that generate fine mist. A proactive approach focuses on preventing exposure in the first place, then controlling and monitoring what remains.

COSHH-based approach: assess, control, review

COSHH requires employers to assess health risks from hazardous substances and prevent or adequately control exposure. For MWFs, this normally includes:

• Identifying exposure routes: mist at point of use, maintenance tasks, sump cleaning, fluid mixing, decanting, and spill clean-up.
• Assessing who is at risk: machine operators, setters, cleaners, maintenance engineers, contractors, and anyone working nearby.
• Implementing controls: engineering controls first, then safe systems of work, hygiene measures, and suitable PPE.
• Checking effectiveness: inspections, monitoring, fluid condition checks, and supervision.
• Reviewing routinely: after process changes, incidents, complaints of symptoms, or results that show controls are not effective.

Practical control measures that reduce exposure

Engineering controls

• Local exhaust ventilation (LEV) and mist capture sized for the machine and process.
• Machine enclosures, guards, and correctly fitted doors/panels to reduce aerosol escape.
• Optimised nozzle direction and pressure to minimise atomisation and overspray.
• Effective filtration and fluid management to reduce tramp oil and contamination.

Safe working practices

• Minimise skin contact by using tools for clearing swarf and handling wet components rather than bare hands.
• Keep lids on sumps, mixing tanks, and containers where possible to reduce aerosol generation and contamination.
• Prevent spread by cleaning drips and small leaks promptly before they become slip hazards or prolonged contact risks.
• Use clear procedures for fluid mixing, top-ups, and biocide additions (only by trained, authorised staff).

Personal protective equipment (PPE)

• Select gloves compatible with the specific fluid and task, and replace when damaged or contaminated.
• Use eye/face protection where splashing is possible, especially during maintenance and cleaning.
• Where mist exposure cannot be adequately controlled, assess the need for respiratory protection as part of the wider COSHH controls.

Hygiene and skin care

• Provide suitable handwashing facilities with mild cleansers and skin conditioning creams.
• Discourage cleaning hands with solvents or harsh degreasers, which can increase dermatitis risk.
• Keep workwear clean and dry where possible, and manage laundering to avoid re-exposure.

Monitoring and maintenance: keeping fluids in a safe condition

Regular monitoring of fluid composition and exposure levels is vital to maintaining a safe working environment. A consistent regime typically includes concentration checks, contamination indicators, housekeeping inspections, and planned maintenance schedules. Good records help demonstrate control, support continuous improvement, and make it easier to spot patterns before they become incidents.

For practical guidance on workshop coolant risks and clean-up considerations, see our dedicated resource here: Coolants: safe handling, spill risks and practical clean-up.

For ongoing checks and site routines, our inspection-focused guidance is here: Regular inspections and monitoring.

Training, competence, and incident response

Even strong controls can fail if staff are not trained to use them properly. Training should cover safe use of MWFs, recognising early symptoms (for example, dermatitis or breathing irritation), correct PPE use, and what to do during spills, leaks, or maintenance tasks that create higher exposure.

Serpro training resources can be found here: Serpro spill training.

General spill prevention and response guidance is available here: Spill management best practice guidelines.

Waste handling and compliance

Used coolant and contaminated absorbents may be controlled waste, depending on the fluid type and contamination. Storage, labelling, segregation, and disposal should follow your site procedures and relevant regulations. Strong compliance reduces the risk of enforcement action and supports a safer workplace.

See our overview of compliance considerations here: Regulatory compliance.

Related guidance for chemical hazards

MWF systems may involve additives, cleaners, biocides, and other chemicals. If you also manage chemical spill risks on site, this guidance may help with response priorities and safe methods:

Chemical spill management

External resources (HSE and industry guidance)

• HSE: Metalworking fluids
• HSE: HSE and metalworking fluids (programme and supporting information)
• HSE: COSHH (Control of Substances Hazardous to Health)
• UKLA/HSE Good Practice Guide: Safe handling and disposal of metalworking fluids (PDF)

Next steps

If you are reviewing your MWF controls, start with a COSHH risk assessment that focuses on where mist and skin contact occur, then prioritise engineering controls, monitoring routines, and training. If you need help selecting spill response products for coolant and MWF incidents, use our Coolants resource as a starting point, and build your site procedures around the risks specific to your processes and machines.