Key Messages for Duty Holders

1. LEV Must Be Effective, Not Just Installed

The workplan repeatedly focuses on whether exposure is actually controlled.

For CNC machining operations HSE inspectors were directed to assess:

• Whether machines are enclosed
• Whether LEV is fitted and operating correctly
• Whether extraction removes mist before doors are opened
• Whether operators are exposed during loading, unloading or cleaning operations
• Whether compressed air is being used in ways that increase aerosol generation

This reinforces a common inspection finding:

Installing LEV alone is not enough. Employers must demonstrate that exposure remains adequately controlled in normal production conditions.

2. Metalworking Fluid Management Is Critical

The document makes clear that health risks arise not only from the original fluid concentrate but also from:

• Bacterial contamination
• Fungal contamination
• Fluid degradation
• Biocides and additives
• Metal fines
• Tramp oils and process contaminants

HSE places significant emphasis on fluid quality management because deteriorating fluids can increase both respiratory and skin disease risks.

3. Exposure Should Be Reduced ALARP

A particularly important point is that HSE does not rely on a workplace exposure limit (WEL) for water-mix MWF mist.

The previous HSE guidance value was withdrawn following investigations where workers developed occupational asthma despite exposures below the former guidance level. HSE therefore expects exposure to be reduced as low as reasonably practicable (ALARP).

This is highly relevant when assessing LEV performance because achieving a numerical concentration target alone may not demonstrate adequate control.

4. Health Surveillance Is Expected

The workplan reflects HSE’s broader position that workplaces using welding processes and MWFs should have appropriate arrangements for:

• Respiratory health surveillance
• Skin surveillance
• Early identification of occupational disease
• Investigation of symptoms and trends

What LEV Professionals Should Take From This Document

When assessing fabrication or machining facilities, practitioners should pay particular attention to:

Welding Processes

• Hood positioning
• Capture effectiveness
• Worker behaviour
• Enclosure opportunities
• Airflow verification
• Maintenance arrangements

CNC and Machining Operations

• Machine enclosure integrity
• Extraction effectiveness
• Door opening delays
• Mist escape pathways
• Cleaning methods
• Use of compressed air

Management Controls

• LEV examination and testing records
• Planned maintenance systems
• MWF management programmes
• Operator training
• Health surveillance systems
• Exposure verification methods

The workplan shows that HSE inspectors are instructed to consider both engineering controls and the wider management system supporting them.

Further Resources

HSE – Metalworking Fluids Topic Pages

Comprehensive guidance covering:

• Fluid management
• Contamination
• Legionella
• Health effects
• Control measures

UKLA / HSE Good Practice Guide for Safe Handling and Disposal of Metalworking Fluids

Industry-recognised guidance on:

• Fluid maintenance
• Exposure control
• LEV considerations
• Health surveillance
• Disposal procedures

Recommended Learning

• HSG258 – Controlling Airborne Contaminants at Work
• COSHH Essentials for Machining with Metalworking Fluids
• Welding Fume Control Strategies
• MWF Quality Monitoring and Management Systems

Thought Leadership

This workplan highlighted an important shift in occupational hygiene and exposure control.

Historically, many organisations focused heavily on airborne measurement results.  HSE’s approach to metalworking fluids increasingly recognises that exposure control is influenced by a combination of:

• Equipment design
• LEV performance
• Fluid quality management
• Worker practices
• Maintenance standards
• Organisational culture

For LEV professionals, this means that successful control of MWF mist and welding fume requires a systems-based approach. Effective extraction remains critical, but long-term health protection depends equally on how those controls are managed, maintained and integrated into day-to-day operations.