Local exhaust ventilation (LEV) systems protect workers from breathing in hazardous substances — dust, fumes, vapours, and gases. If your business uses an LEV system, UK law requires it to be thoroughly examined and tested at regular intervals. But how often, exactly? And what counts as a proper test?
This guide explains LEV testing frequency requirements under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), what the examination involves, and how to stay compliant.
What Is an LEV System?
An LEV system is an engineering control designed to capture airborne contaminants at or near the point of generation, preventing them from entering the worker's breathing zone. Common types include:
- Welding fume extraction — portable and fixed units used in fabrication, manufacturing, and construction
- Woodworking dust extraction — ducted systems connected to saws, planers, sanders, and routers
- Spray booth extraction — for paint spraying, coating, and finishing processes
- Fume cupboards — used in laboratories and chemical processing
- Grinding and cutting extraction — for metalworking, stone cutting, and similar processes
- Chemical process ventilation — extraction from mixing, blending, and dispensing operations
- Bakery dust extraction — flour and additive dust control in food processing
If the system is designed to control exposure to a substance hazardous to health, it is almost certainly an LEV system covered by COSHH.
How Often Does LEV Testing Need to Happen?
The baseline legal requirement is clear:
LEV systems must be thoroughly examined and tested at least every 14 months.
This is set out in Regulation 9 of the Control of Substances Hazardous to Health Regulations 2002 (COSHH). The 14-month interval is a maximum — not a target. More frequent testing may be needed where:
- The LEV system is critical to controlling exposure to highly toxic substances (e.g., isocyanates, respirable crystalline silica, asbestos)
- The system is in a harsh or demanding environment that accelerates wear
- Previous examinations have revealed deterioration or declining performance
- A risk assessment identifies the need for shorter intervals
Industry-Specific Guidance
Some industries have specific guidance from the HSE that recommends shorter intervals:
| Industry / Process | Recommended Interval |
|---|---|
| Most LEV systems (general) | Every 14 months |
| Fume cupboards (laboratories) | Every 14 months |
| Welding fume extraction | Every 14 months |
| Woodworking dust extraction | Every 14 months |
| Spray booths (paint/coating) | Every 14 months |
| LEV controlling exposure to carcinogens | Consider 6–12 months |
| Systems with a history of problems | Consider 6–12 months |
The 14-month interval gives a small overlap margin beyond 12 months, allowing flexibility in scheduling without creating a gap in compliance.
What Does a LEV Thorough Examination Involve?
A thorough examination and test under COSHH is far more than a visual check. The competent person will:
- Visually inspect the entire system — hoods, ducting, filters, fans, and discharge points
- Measure airflow at each hood or capture point using calibrated instruments
- Assess capture effectiveness — is the system actually capturing contaminants at the point of generation?
- Check all components — filters, dampers, seals, flexible connections, motor and fan condition
- Verify control measures — are face velocities and capture velocities adequate for the substances being controlled?
- Test alarm and interlock systems if fitted (e.g., airflow monitors, filter pressure drop alarms)
- Issue a written report in the prescribed format, detailing measurements, condition, and any deficiencies
The report must state whether the system is in efficient working order, in good repair, and continuing to be effective in controlling exposure.
Who Can Test LEV Systems?
COSHH requires the examination and test to be carried out by a competent person. There is no single mandatory qualification, but the competent person must have:
- Knowledge of the principles of LEV design and operation
- Understanding of the substances being controlled and the exposure risks
- Practical experience in testing LEV systems of the type being examined
- Access to appropriate instrumentation (anemometers, pitot tubes, dust lamps, etc.)
The HSE publication HSG258 ("Controlling Airborne Contaminants at Work") provides detailed guidance on what constitutes competence for LEV testing. Many inspection bodies and occupational hygiene consultancies offer LEV testing as a specialist service.
What Happens If You Miss a Test?
Failure to have your LEV system examined and tested within the required interval is a breach of COSHH Regulation 9. The consequences can include:
- HSE improvement notices requiring you to have the system tested immediately
- HSE prohibition notices if the system is believed to be ineffective — this can shut down the process it supports
- Fines — there is no upper limit on fines for health and safety offences in the Crown Court
- Prosecution — particularly if worker exposure has exceeded workplace exposure limits
- Civil claims — if a worker develops an occupational disease (e.g., occupational asthma, silicosis) due to inadequate LEV
Beyond enforcement, if your LEV system fails and workers are exposed, the business faces claims under employers' liability insurance, potential RIDDOR reporting obligations, and reputational damage.
Keeping Track of LEV Testing Dates
For businesses with multiple LEV systems across different locations, managing examination dates can be complex. Best practice includes:
- Maintaining a central register of all LEV systems, their locations, and examination due dates
- Scheduling examinations with enough lead time that the 14-month interval is never breached
- Using digital inspection management platforms where available — some providers offer automated reminders and online report storage
- Keeping all examination reports for at least 5 years (COSHH requirement)
Frequently Asked Questions
Does a brand new LEV system need testing?
Yes. A new LEV system should be commissioned and tested when it is first installed to verify it meets its design specification. The 14-month examination cycle then starts from the commissioning date.
Can I test my own LEV system?
You can if you have the competence and equipment to do so. In practice, most businesses use an external specialist because they bring independent judgement, calibrated instruments, and knowledge of current best practice.
What is the difference between LEV testing and maintenance?
LEV testing (thorough examination and test) is a formal, independent assessment of whether the system is effective. Maintenance (cleaning filters, replacing belts, tightening connections) keeps the system running but does not replace the statutory examination.
Does the 14-month rule apply to all LEV systems?
It applies to all LEV systems used to control exposure to substances hazardous to health under COSHH. If your system is not controlling exposure to a hazardous substance (e.g., it is purely for comfort ventilation), COSHH Regulation 9 may not apply — but other regulations may.
What if my LEV system fails its test?
The competent person will detail the deficiencies in the report. You must take action to repair or replace the system. Depending on the severity, you may need to stop the process until the LEV is effective again, or implement temporary controls to protect workers.
Compare LEV Testing Providers
LEV examination prices vary depending on the system type, number of extraction points, and your location. Comparing quotes from multiple providers ensures you get competent testing at a fair price.
Compare Engineering is a UK comparison platform for statutory engineering inspections, including LEV testing. Request and compare quotes at compareengineering.com.
This article is for general guidance only and does not constitute legal advice. Always consult a competent person or occupational hygienist for advice specific to your circumstances.