New HSE Video Series: How to Control Metalworking-Fluid (MWF) Mist During CNC Machining
HSE has released a practical four-part video series focusing on how to control exposure to metalworking-fluid (MWF) mist during CNC machining. The films demonstrate how effective local exhaust ventilation (LEV), visualisation techniques and straightforward monitoring tools can significantly reduce respiratory and skin risks for operators.
Metalworking fluids are essential for cooling and lubricating cutting operations, but the mist generated can lead to occupational asthma, hypersensitivity pneumonitis and dermatitis if not properly controlled. The new videos give employers concise demonstrations they can replicate on the shop floor to strengthen compliance with COSHH and improve day-to-day operator protection.
What the four new HSE videos cover
HSE’s new series consists of four short films designed for toolbox talks, inductions and refresher training. Each video provides actionable guidance for assessing and improving exposure controls:
1. LEV to control worker exposure to MWF mist
A demonstration of how correctly designed, positioned and commissioned LEV equipment captures mist at source. The video highlights key design principles, the importance of enclosure, the role of filtration and tips for ensuring effective capture.
2. Monitoring methods for MWF mist
Explains simple, practical techniques such as dust lamps, smoke pens and direct-reading aerosol monitors. These tools help you visualise mist behaviour, compare machines and identify priority areas for improvement.
3. Assessing control of MWF mist during CNC machining using monitoring methods
Shows how to run short monitoring sessions during typical CNC cycles. The video illustrates how different machining operations can generate varying mist levels and where additional controls may be needed.
4. Monitoring methods to check LEV for MWF mist
Provides step-by-step practical checks for routine LEV assessment, including airflow indications, dust-lamp checks and clearance-time tests. The video demonstrates how to embed these checks into regular maintenance procedures.
Why this matters for your workshop
MWF mist is a recognised cause of occupational lung disease and remains an area of active HSE attention. Key challenges frequently seen during inspections include:
- Poor LEV design or use
- Operators opening machine doors before mist has cleared
- Ineffective or unmonitored filtration
- Inadequate fluid-quality management
- Limited recording of checks and LEV performance
- Lack of health surveillance where exposure remains possible
These new videos provide clear demonstrations that show what “good” looks like and help employers benchmark their own practices.
A seven-step action plan for employers
Use the videos as part of a structured improvement programme. The following steps are practical, inexpensive and effective:
1. Show the videos to operators and supervisors
Use the films as part of a 10–15 minute toolbox talk or induction module. The visual demonstrations help reinforce safe behaviour and clarify the reasons for engineering controls.
2. Risk-rate your CNC machines
Conduct a walk-through using a dust lamp or aerosol monitor to identify which machines generate the most mist. Prioritise these machines for enclosure improvements, LEV review or process-change considerations.
3. Commission and document LEV
Ensure LEV hoods are correctly sized and positioned, that enclosures are used effectively and that commissioning records — including clearance times — are up-to-date and accessible.
4. Introduce a routine LEV check schedule
Use a standard checklist to record weekly airflow indications, dust-lamp checks, filter condition and enclosure performance. Maintain a simple LEV logbook and ensure responsible persons are clearly identified.
5. Manage fluid quality effectively
Check concentration, pH, odour and bacterial contamination as part of a structured fluid-management programme. Poor coolant condition increases mist production and health risks.
6. Review and update safe working procedures
Avoid compressed-air cleaning, limit door-opening until after clearance times and ensure operators know how to position LEV hoods correctly. Consider interlocks or time-delay systems where appropriate.
7. Apply health surveillance where required
If workers are exposed to MWF mist, health surveillance for skin and respiratory symptoms is required under COSHH. Implement a structured programme and ensure early-reporting systems are in place.
Recommended next steps which Outsource Safety can assist with
- Toolbox talk outline: play one video → run a short Q&A → agree two machine-specific improvements.
- LEV quick-check sheet: hood condition, visual capture check, airflow gauge, filter state, clearance time, required actions.
- Machine-priority register: machine ID, mist-assessment result, action required, target date, assigned person.
Further resources for deeper understanding
- HSE metalworking-fluids main guidance pages
- COSHH Essentials: MW0–MW5 (Machining with metalworking fluids)
- HSE YouTube playlist: “Metalworking fluid mist” – the full four-video series
Final thoughts
HSE’s updated video materials make it easier than ever to demonstrate a clear, evidence-based approach to controlling MWF mist. By combining simple monitoring methods, effective LEV and structured checks, employers can reduce ill-health risks, improve operator confidence and strengthen COSHH compliance.
A practical next step is to run a short session with your CNC operators using the new films, followed by a quick dust-lamp survey on your highest-use machines – or we can do this for you if you are a retained client under Safety~net support. Small, visible improvements can deliver significant gains in both safety and operational reliability. If you need specific help and you are a retained client (or would like our help on this) please contact Roger Hart or ask for a call back from one of our safety experts







