Local Exhaust Ventilation (LEV) systems play a vital role in protecting employees from hazardous substances in the workplace. But even a well-designed system can lose effectiveness over time. To stay compliant with the Control of Substances Hazardous to Health (COSHH) Regulations, every LEV system must undergo a Thorough Examination and Test (TExT) at regular intervals.

If you are responsible for health and safety in your organisation, understanding what happens during this process – and what your responsibilities are – is essential.

What is a Thorough Examination and Test?

A Thorough Examination and Test is a formal inspection of your LEV system to make sure it continues to protect employees by adequately controlling airborne contaminants such as dusts, fumes and vapours.

According to the Health and Safety Executive (HSE), a competent person must carry out the test at least once every 14 months. Some processes require more frequent checks, such as:

• Welding or soldering – every 6 months

• Woodworking dust extraction – every 12 months

• Carcinogenic or mutagenic materials – every 6 months

These timeframes ensure that system performance remains consistent and that exposure stays within legal limits.

What the test involves

During a Thorough Examination and Test, an accredited engineer will inspect and measure several aspects of your LEV system. This includes:

1. Visual inspection
   Checking the condition of hoods, ducts, filters and fans for wear, corrosion or blockage.

2. Airflow and pressure measurements
   Recording the airflow velocity at hoods and throughout the system to confirm that contaminants are being effectively captured and removed.

3. Filter and duct integrity
   Ensuring filters are in good condition and that duct joints and seals are airtight.

4. System controls and indicators
   Verifying that airflow gauges, alarms or pressure indicators are functioning correctly.

5. Smoke or dust tests
   Where applicable, using smoke or dust to visually confirm capture efficiency and airflow direction.

6. Performance assessment
   Comparing results to the system’s original commissioning data to check that it still meets design specifications.

7. Reporting
   Providing a written report detailing measurements, test results, observations and any remedial actions needed.

What your report should include

A LEV system test report that follows HSG258 guidance and contains the key performance details will satisfy the record-keeping requirements under the COSHH regulations.

• The name and address of the employer and site tested

• The name of the person or company carrying out the test

• Details of each LEV system and process examined

• Test results and assessment of system performance

• Identification of any defects or repairs required

• Recommendations and next test date

HSG258 provides detailed guidance on the design, commissioning, operation, maintenance and testing (Thorough Examination & Test) of LEV systems

Keeping these reports on file is a legal requirement and helps demonstrate compliance during HSE inspections.

Common issues discovered during testing

Regular TExT helps identify problems early. Common findings include:

• Blocked or damaged filters reducing airflow

• Duct leaks allowing contaminants to escape

• Poor hood positioning after equipment changes

• Incorrect fan speed or motor wear

• Missing or outdated logbooks and documentation

Addressing these issues promptly ensures your system continues to protect employees and avoids enforcement notices.

 

How to prepare for a TExT

Before your scheduled inspection:

• Clean or replace filters where needed

• Check that all hoods are accessible

• Review previous reports to confirm any recommendations were completed

• Ensure operators know how to adjust and position hoods correctly

A well-prepared system makes the inspection smoother and helps your engineer provide accurate results.

After the inspection

If your system passes, you will receive a new test certificate confirming compliance. If faults are identified, your engineer will recommend remedial actions. Repairs should be completed as soon as possible, and in serious cases the system may need retesting once corrective work is finished.

It is good practice to log maintenance, airflow checks and repairs between formal tests. This evidence demonstrates proactive management and supports ongoing compliance.

Why use a qualified LEV specialist

Only a competent person should carry out a Thorough Examination and Test. BOHS-qualified engineers have the training and equipment to evaluate performance accurately. Using a recognised specialist ensures that your system meets HSE standards and that your documentation will stand up to regulatory scrutiny.

LEV Engineering Ltd provide nationwide LEV testing, service contracts and system maintenance, ensuring your workplace remains safe, efficient and compliant all year round.

Contact Us Today

If your LEV system is due for its next examination or you are unsure when it was last tested, contact LEV Engineering Ltd. Our qualified engineers can assess your system, carry out a full TExT and advise on any improvements needed to keep your business compliant.