Monitoring and Controlling Exposure to Metalworking Fluids: Protecting Workers and Maintaining Compliance

Metalworking fluids (MWFs) are essential in modern machining operations, providing lubrication, cooling, and corrosion protection. However, their benefits come with significant health risks if exposure is not adequately controlled. Mist, vapour, and aerosol generated during machining can be inhaled, and prolonged contact with fluids can irritate or damage the skin. Without effective monitoring and control strategies, workers may face severe occupational health conditions, including dermatitis, occupational asthma, and long-term lung diseases.

For employers, compliance with COSHH and HSE guidance is not optional—it is a legal and moral responsibility. Effective control of MWF exposure safeguards employee wellbeing, improves productivity, and prevents costly downtime or enforcement action.

Understanding the Health Risks of Metalworking Fluids

MWFs can contain complex mixtures of oils, water, additives, biocides, and contaminants, such as metal fines or microbial growth. When machining operations generate mist or aerosol, the particles become airborne and can be inhaled deeply into the lungs.

Inhalation Risks

Breathing in MWF mist is associated with:

• Respiratory irritation

• Occupational asthma

• Hypersensitivity pneumonitis

• Chronic lung diseases from long-term exposure

These conditions often develop gradually, making continuous monitoring and early detection vital.

Skin Contact Risks

Long-term skin exposure can lead to:

• Dermatitis

• Oil acne

• Increased sensitivity to chemical additives

• Infection through broken or irritated skin

Good hygiene practices, alongside engineering controls, are essential in minimising contact.

Legal Requirements: COSHH and HSE Expectations

Under COSHH, employers must assess the risks from MWFs, implement appropriate control measures, and ensure ongoing monitoring and health surveillance. HSE specifically highlights that metalworking fluid mist must be controlled at source and exposure must be reduced as far as reasonably practicable. Regular LEV testing (as required annually for most systems) is a key part of meeting these duties.

Monitoring Exposure: Essential Steps for Compliance

Effective monitoring is the foundation of safe metalworking fluid management. Employers should implement:

1. Airborne Mist Monitoring

Periodic air sampling ensures that mist levels remain below Workplace Exposure Limits (WELs). In the absence of a specific WEL for MWF mist, HSE recommends keeping concentrations as low as reasonably practicable. Air monitoring helps:

• Confirm LEV systems are performing effectively

• Detect rising mist levels caused by equipment wear or poor housekeeping

• Provide evidence of compliance for audits

2. Fluid Quality Checks

MWF condition directly impacts mist generation and worker health. Regular checks should include:

• Concentration measurements

• pH monitoring

• Tramp oil levels

• Bacterial and fungal counts

Maintaining fluid within the manufacturer’s recommended parameters significantly reduces risk.

3. Health Surveillance

Employees exposed to MWF mist should be enrolled in an appropriate health surveillance programme, including skin checks and respiratory questionnaires. Early intervention prevents minor symptoms from becoming chronic conditions.

Controlling Exposure: Engineering and Administrative Measures

1. Local Exhaust Ventilation (LEV)

LEV is the most effective engineering control for removing mist at the source. Properly designed LEV systems—such as enclosures, capture hoods, or custom solutions integrated into machine tools—ensure contaminated air is extracted before workers inhale it.

A correctly specified and maintained LEV system also contributes to:

• Reduced contamination of the workshop environment

• Lower cleaning costs

• Improved machine visibility and operator comfort

To stay compliant, LEV systems require routine maintenance and statutory testing at least once every 14 months. At A-Mac Environmental, our P601/P602-qualified engineers design, supply, install, and test LEV systems for machining environments across Scotland, ensuring full COSHH and HSG258 compliance.

2. Machine Enclosures and Guards

Keeping machines enclosed minimises mist escape. Doors, covers, and interlocks should be maintained so that operators are not exposed during machining operations.

3. Good Housekeeping and Maintenance

Simple practices have a significant impact, such as:

• Regular cleaning of surfaces to prevent residue buildup

• Immediate repair of leaks or damaged seals

• Proper storage and disposal of contaminated materials

4. Operator Training

Workers must understand:

• The health hazards of MWF exposure

• How to use LEV systems correctly

• How to handle fluids safely

• Personal hygiene and protective equipment requirements

Consistent training ensures that control measures remain effective day to day.

Why Proactive Control Benefits Your Business

Beyond compliance and safety, effective management of MWF exposure delivers several operational advantages:

• Increased tool life and improved machining performance

• Fewer employee absences linked to skin or respiratory illness

• Lower fluid usage through improved condition management

• Reduced risk of HSE enforcement or costly claims

A well-controlled environment is both safer and more productive.

How A-Mac Environmental Can Support Your MWF Exposure Control

A-Mac Environmental provides full turnkey LEV and compliance services to help industrial sites manage exposure to metalworking fluids. Our offering includes:

• LEV system design, supply, and installation

• Routine LEV testing and COSHH-compliant reporting

• Extraction systems for mist, fumes, and dust

• Site assessments and risk evaluations

• Maintenance, repairs, and aftercare packages for the LEV system

Our engineers hold P601 and P602 qualifications, ensuring all systems meet HSG258 standards and are fully compliant with UK regulations.

Conclusion

Monitoring and controlling exposure to metalworking fluids is not only a regulatory requirement but an essential part of safeguarding employee health and ensuring efficient, reliable manufacturing operations. By combining air monitoring, robust LEV solutions, fluid quality management, and effective training, employers can significantly reduce risks and maintain a safer working environment.

If you require support with LEV design, mist extraction, or COSHH compliance for metalworking processes, A-Mac Environmental can provide a tailored solution that meets your operational and regulatory requirements.