What Is a Local Exhaust Ventilation (LEV) System and Does Your Business Need One?

If your business produces dust, fumes, vapours, or other airborne substances, it’s important to consider how these could affect your employees’ health. As an employer in Northern Ireland, you are legally responsible for managing these risks and creating a safe working environment. 

One of the most effective ways to manage this risk is by using a Local Exhaust Ventilation (LEV) system. LEV works by capturing harmful substances directly at the source, preventing them from spreading through the workplace or being inhaled by your staff.

In this article, we’ll explain an LEV system, how it works, and how to determine whether your business needs one. We’ll also discuss your legal responsibilities under COSHH, what’s at stake if you don’t take action, and how DevineAir can support you in creating a safer, cleaner working environment.

What Is a Local Exhaust Ventilation (LEV) System?

A Local Exhaust Ventilation (LEV) system is a type of engineering control used to extract airborne contaminants directly from the source, before they can disperse into the air your team breathes.

Rather than relying on general ventilation (which dilutes contaminated air), LEV is targeted. It captures pollutants as they’re generated and removes them through a series of ducts and filters.

An LEV system typically includes:

• A hood or capture device: Positioned close to the contaminant source.
• Ducting: To transport the air and contaminants away from the work area.
• An air cleaner or filter: Removes or neutralises the hazardous material.
• A fan: Creates airflow through the system.
• A discharge outlet: Safely vents the cleaned air or exhausts it outside.

Properly designed and maintained LEV systems can significantly reduce the risk of respiratory illness, long-term health conditions, and accidents caused by poor air quality.

Do You Need an LEV System?

If your business involves any activity that generates airborne contaminants, you should seriously consider whether a Local Exhaust Ventilation (LEV) system is required. LEV is not a luxury—it's often a legal and practical necessity.

Ask yourself the following:

1. Do your work processes create harmful airborne substances?

Many common workplace tasks release harmful substances into the air. You may need LEV if you carry out:

• Welding or soldering – Releases metal fumes and gases.
• Woodworking – Produces fine dust that can damage lungs over time.
• Paint spraying or coating – Emits solvent vapours and particulates.
• Grinding, cutting, or sanding – Generates respirable dust.
• Chemical mixing or decanting – Can release toxic vapours or aerosols.
• Laboratory work – Often involves exposure to hazardous biological or chemical agents.

If you’re performing these kinds of activities—even occasionally—your workers may be at risk of inhaling substances that could cause asthma, cancer, or other serious health problems.

2. Are you relying on general ventilation or PPE alone?

Opening a window or using a fan will not protect your employees from fine dust or fumes. Likewise, under UK law, relying solely on personal protective equipment (PPE) like masks or respirators isn’t enough.

The COSHH regulations clarify that engineering controls like LEV should be your first line of defence wherever possible. PPE should only be a backup measure, not your primary solution.

3. Do you know what substances you're exposing your staff to?

You’re legally required to assess and identify hazardous substances in your workplace. If you don’t know what you're dealing with, you can’t control it.

For example:

• Is the dust you create classified as a ‘respirable crystalline silica’?
• Are the vapours from your chemicals known to be carcinogenic or cause asthma?
• Are you using materials with Workplace Exposure Limits (WELs)?

LEV systems help reduce airborne concentrations of such substances below legal limits, protecting your workers and ensuring compliance.

The list of substances and WELs is available on the UK HSE Workplace Exposure Limits Guide (EH40), which is also applicable in Northern Ireland.

4. Have you had complaints, signs of exposure, or near misses?

Here are some red flags that may indicate you need LEV:

• Persistent complaints of cough, headaches, sore throats, or eye irritation
• Excessive build-up of dust, mist, or smoke in the workspace
• Strong chemical odours lingering in the air
• Respirators or dust masks are getting clogged quickly
• Employees regularly use fans to ‘clear the air’
• Near misses involving poor visibility or breathing difficulty
  

If any of these sound familiar, it’s a strong indication that airborne hazards are not being adequately controlled.

5. Do you want to future-proof your business?

Even if you’re not currently required by law to have LEV, regulations evolve, and enforcement is tightening, especially in high-risk sectors. Taking proactive steps now can:

• Reduce the risk of enforcement action from HSENI
• Minimise long-term health claims
• Demonstrate a culture of safety and responsibility

Put simply, LEV protects your people—and your business—from avoidable harm.

What Happens Without LEV?

Failing to control exposure to harmful substances can lead to:

• Respiratory illnesses, such as asthma, COPD, or silicosis
• Occupational dermatitis or skin irritation
• Reduced concentration, fatigue, and increased accidents
• Legal consequences, including enforcement notices, fines, or prosecution
• Civil claims from employees suffering ill health

In short, if your processes are creating dangerous airborne materials, ignoring LEV could cost more than just money—it could cost your team’s well-being and your business’s reputation.

Key Benefits of Installing an LEV System

Besides meeting legal obligations, LEV systems bring many practical and financial benefits.

1. Protect Your People

Your employees are your most valuable asset. LEV reduces the risk of exposure-related illnesses, making your workplace safer and healthier.

2. Ensure Legal Compliance

By properly implementing LEV and maintaining it, you demonstrate that your business meets COSHH requirements and avoids costly penalties.

3. Boost Productivity

Cleaner air improves concentration and reduces sick leave. Staff work better when they’re not breathing in harmful substances.

4. Enhance Reputation

Customers, auditors, and staff all value companies that take health and safety seriously. LEV helps you lead by example.

Common Mistakes to Avoid

When it comes to LEV, cutting corners often leads to bigger problems. Here are some pitfalls to steer clear of:

• Using general ventilation instead of LEV
• Incorrect hood design or poor placement
• Infrequent maintenance or skipped inspections
• Not training staff to use the system properly
• Not reviewing system performance after changes in work processes

The Role of Professional Support

Designing, installing, and maintaining an LEV system isn't a box-ticking exercise—it requires expert knowledge. Off-the-shelf or DIY setups often fall short of regulatory standards, leaving you vulnerable.

Professional support ensures that:

• Your system matches the exact processes and contaminants involved
• Testing and certification meet legal standards
• Your team is trained, and your documentation is in order

Your Employees’ Health Matters

A properly installed and maintained LEV system isn’t just a piece of equipment. It’s a vital part of your health and safety strategy. If your processes generate harmful airborne substances, an LEV system may be useful and legally essential.

By taking action now, you protect your team, business, and future.

At DevineAir, we help businesses across Northern Ireland assess, implement, and maintain effective LEV systems that protect workers and satisfy all compliance requirements.

With over 20 years' experience in environmental health and safety services, we understand the specific needs of different industries—from light workshops to large-scale manufacturing plants.

Our expert team is trained to the highest level, and we work with a network of trusted professionals to deliver top-tier support at every stage. Let’s make your workplace safer.

Contact DevineAir today to book a site assessment or speak to one of our consultants.