Local exhaust ventilation, or LEV, is any system that captures dust, fumes, vapour or mist at the point where it’s made, before workers breathe it in. Under COSHH, the Control of Substances Hazardous to Health Regulations, employers who rely on LEV to protect workers must keep it working and have it tested. This guide explains what LEV is, what a thorough examination and test involves, and how often it’s needed.
What counts as LEV
LEV covers a wide range of equipment. Examples include:
- dust extraction on woodworking machines and saws
- fume extraction for welding and soldering
- spray booths and paint extraction
- fume cupboards in laboratories and school science rooms
- extraction on mixing, weighing or bagging processes in food production
A typical system has a hood or enclosure to capture the contaminant, ductwork, sometimes a filter or air cleaner, a fan and a discharge. A general kitchen canopy is normally treated as kitchen ventilation rather than LEV, and is cleaned to TR19® Grease.
What the law requires
The Health and Safety Executive says LEV must receive a thorough examination and test (often called TExT) at least every 14 months, with a few exceptions where a shorter interval applies, and that it must be carried out by a competent person (HSE, Local exhaust ventilation). Unlike TR19, which is an industry specification, this is a legal requirement under COSHH for employers who use LEV to control exposure.
The point of the test is simple. If LEV is meant to stop workers breathing in harmful dust or fumes, you need to know it still does. Systems wear, ducts get damaged or blocked, and processes change. A system that passed when it was fitted may not be good enough now.
The HSE pages also explain the duties of suppliers, employers and examiners, and are well worth reading if you manage LEV on site.
Need it done? Duct Doctor cleans and tests kitchen extract and ventilation systems across London and the South East, with a certificate and photo report after every clean. Get a fixed quote.
What a thorough examination and test involves
A TExT checks that the system is still doing the job it was designed to do. It usually includes:
- a visual inspection of hoods, ductwork, filters, fan and discharge for damage, wear and build-up
- measurements of airflow and pressures at key points
- checks that contaminants are being captured, for example with a smoke test or dust lamp
- comparing results with the system’s design figures or previous tests
- a written report, with any repairs or improvements needed
Duct Doctor carries out LEV testing across London and the South East.
Records and the logbook
Keep the test report for each system, along with a logbook of routine checks and maintenance. Day-to-day checks between tests, such as making sure the airflow indicator is in range and hoods are in the right position, help spot problems early. If a test finds faults, record the repairs and any retest. HSE guidance covers what records should be kept and for how long (HSE).
Keeping LEV working between tests
- Train staff to use hoods and enclosures properly.
- Don’t move capture hoods away from the work.
- Change or empty filters and collection bins as the maker advises.
- Report damaged ductwork, loose joints or a change in fan noise.
- Keep ductwork clean. Dust build-up reduces airflow and can be a fire or explosion risk in some processes.
Where LEV ductwork has become dirty, cleaning may be needed before the system can perform as it should. See our ventilation duct cleaning service.
Quick answers
How often must LEV be tested?
HSE says at least every 14 months, with a few exceptions that need more frequent testing.
Who can carry out an LEV test?
A competent person with the right knowledge, training and experience, as HSE guidance explains.
Is a kitchen canopy LEV?
A general kitchen canopy is normally treated as kitchen ventilation and cleaned to TR19 Grease.
Related services
More advice
- School Kitchen Extract Cleaning: Holiday Planning
- TR19 Air Explained: Ventilation Hygiene for Buildings
- Air Handling Unit Cleaning: A Practical Guide
- The Responsible Person Under the Fire Safety Order
- All advice
This guide is general information. It isn’t legal or insurance advice: check your own policy wording and lease, and speak to a qualified adviser about your fire risk assessment.