Local Exhaust Ventilation System: The Backbone of Industrial Air Safety

In any industrial or manufacturing environment, the air your employees breathe matters more than most realise. A well-designed Local Exhaust Ventilation (LEV) system is the backbone of air safety.  Without it, workers are exposed to invisible hazards that can harm their health, reduce productivity, and put your business at risk of non-compliance.

At DevineAir, we understand the importance of keeping the air your team breathes clean and safe. Whether you’re welding, cutting, spraying, or working with chemicals, the air around your processes can become contaminated with dust, fumes, vapours, or mist. 

Let’s explore what these systems do, how they work, why they’re legally required, and how to keep them performing at their best.

What is a Local Exhaust Ventilation System?

A local exhaust ventilation (LEV) system is an engineered control designed to protect workers from breathing in harmful airborne substances. Unlike general room ventilation, LEV systems are designed to capture contaminants directly at the point where they’re generated.

You’ll find LEV systems across a wide range of industries, including:

• Manufacturing and engineering – welding, grinding, metal cutting
• Woodworking – sawdust and wood dust extraction
• Construction – silica, cement, or stone dust control
• Pharmaceuticals and laboratories – chemical fumes and powders
• Automotive and paint shops – solvent vapours and overspray

Every process that generates airborne hazards needs effective local extraction, and that’s where LEV systems become essential.

How a Local Exhaust Ventilation System Works

A well-designed LEV system typically includes five main parts:

1. Hood or capture device – placed near the source to collect contaminated air.
2. Ducting – carries the air from the hood to the filter or air cleaner.
3. Air cleaner or filter unit – removes hazardous particles, dusts, or vapours.
4. Fan – draws air through the system.
5. Discharge outlet – safely releases filtered air back into the atmosphere or recirculates clean air into the workspace.

The key to effective LEV performance is capturing the contaminant as close to the source as possible. If the hood is too far away or if airflow is insufficient, harmful substances will escape into the workspace and expose workers.

The HSE’s HSG258 guidance — “Controlling airborne contaminants at work” — provides practical advice on designing, using, and maintaining LEV systems. You can read it here.

Why Local Exhaust Ventilation Systems Matter

1. Protecting employee health

Every year, thousands of UK workers develop occupational diseases caused by inhaling dusts, fumes, and vapours. Conditions such as asthma, chronic obstructive pulmonary disease (COPD), lung cancer, and silicosis can all result from long-term exposure to poor air quality.

An effective local exhaust ventilation system captures those airborne contaminants before they’re breathed in.

2. Meeting legal requirements

Under the Control of Substances Hazardous to Health Regulations (COSHH), employers must prevent or control exposure to hazardous substances. LEV is one of the most reliable control measures available.

The law also requires employers to ensure that LEV systems are thoroughly examined and tested at least once every 14 months, or more frequently if the process is particularly hazardous. 

Failing to maintain and test your system can lead to enforcement action, fines, and even prosecution — not to mention the risk to your staff’s health.

3. Maintaining productivity and efficiency

Clean air isn’t just about compliance. It’s about efficiency. A properly functioning LEV system keeps equipment cleaner, reduces maintenance costs, and minimises production downtime caused by clogged filters or contaminated machinery. Employees also work better in environments where the air feels clean and fresh.

Legal and Safety Standards You Should Know

If you manage or operate an LEV system, the following standards and regulations apply to you:

• COSHH Regulations 2002 – legal duty to prevent or control exposure.
• HSG258 (HSE) – technical guidance for design, use, and maintenance.
• HSG54 and HSG53 – related to RPE and control of hazardous substances.

To comply, you must:

• Keep design and performance records for each LEV system.
• Ensure testing is carried out by a competent engineer.
• Maintain records of thorough examination and testing for at least five years.
• Provide user training for anyone operating the system.

Compliance isn’t complicated when you have the right support, and it’s always cheaper than dealing with the consequences of neglect.

Signs Your LEV System May Be Underperforming

Even the best LEV system can deteriorate over time. Here are some early warning signs that something’s wrong:

• Dust, mist, or fumes are visible in the air near the process.
• Hoods are not capturing as effectively as before.
• Filters are clogging more often than usual.
• Unusual noises or vibrations from the fan or ductwork.
• Workers reporting respiratory irritation, coughing, or headaches.

If any of these sound familiar, it’s time to arrange an LEV test. Routine maintenance and performance checks are the only way to ensure your system continues to do its job effectively.

What’s Included in an LEV Test

A thorough examination and test (TExT) includes:

• Airflow and velocity measurements.
• Pressure readings and filter inspection.
• Verification of hood and duct performance.
• Comparison against original design specifications.
• A written report detailing findings, compliance status, and any remedial actions.

Testing should always be carried out by a qualified and experienced engineer using calibrated instruments. The results will confirm whether your system meets COSHH standards and continues to provide adequate protection.

Best Practices for Maintaining Your LEV System

To keep your local exhaust ventilation system operating safely and efficiently:

1. Test regularly – at least every 14 months (or more frequently for high-risk processes).
2. Clean hoods and filters – keep them free from buildup and debris.
3. Train operators – ensure staff know how to position and use the extraction correctly.
4. Record everything – keep inspection and maintenance logs up to date.
5. Work with professionals – partner with accredited LEV specialists who understand your industry.

Proactive maintenance helps you avoid breakdowns, stay compliant, and ensure your people are always protected.

Why Choose Professional LEV Services

LEV systems are complex, and even small faults can drastically reduce their effectiveness. Working with a professional testing and inspection team gives you peace of mind that every component is performing as it should.

A competent testing provider will give you:

• Accurate airflow and pressure readings.
• Clear, easy-to-understand reports.
• Practical recommendations for improvement.
• Full compliance documentation for HSE inspection.

When you choose a trusted partner, you’re not just meeting regulations, but you’re safeguarding your people and your reputation.

How DevineAir Can Help

At DevineAir, we understand how critical it is to keep your workplace air clean, safe, and compliant. We provide accurate results, clear reports, and practical advice to ensure your system performs at its best.

Our goal is to make compliance simple. We work around your operations to minimise downtime, offering professional support that helps you identify issues early and maintain full legal compliance.

Aside from LEV system testing, we offer a full range of environmental and health & safety services, including breathing air testing, indoor air quality checks, noise and vibration monitoring, cleanroom validation, and lux level assessments.

At DevineAir, we help businesses across the UK breathe easier and operate smarter. Get in touch today to book your next LEV inspection or discuss a tailored compliance plan for your workplace.