What Happens During an LEV Thorough Examination and Test?

“An LEV test should tell you whether extraction still controls the dust or fume your workers are exposed to – not simply whether the fan turns on.”

If your workplace uses local exhaust ventilation (LEV) to control dust, fumes or vapours, you may have been told to book a Thorough Examination and Test, often shortened to TExT. What actually happens when the examiner visits?

A proper LEV examination checks the condition of the system, measures how it performs and assesses whether it is still capturing or containing the contaminant generated by the work. The examiner then provides a report explaining the findings and any action required.

Jump to:

What Is an LEV Thorough Examination and Test?

Local exhaust ventilation captures airborne contaminants close to where they are generated. Depending on your workplace, that could mean a welding extraction arm, woodworking dust system, spray booth, fume cupboard or on-tool extractor.

Under COSHH, LEV used to control exposure to hazardous substances needs to remain effective and undergo a competent Thorough Examination and Test at the required interval. For most systems, the maximum interval is 14 months; certain processes have shorter intervals. Our separate guide explains how often LEV should be tested.

This article focuses on what the examiner does during the visit and what the employer should expect afterwards.

1. What Happens Before the LEV Test Starts?

The examiner first needs to establish what the system is meant to control and how it is normally used. A system extracting wood dust should not be judged solely on whether its motor runs; the assessment needs to consider the machines, extraction points and working practices it serves.

Where available, the examiner reviews:

• The original commissioning report and intended performance figures
• The LEV user manual, system drawing and logbook
• Previous Thorough Examination and Test reports
• Records of maintenance, repairs or modifications
• The substances and work processes being controlled
• Any changes to machinery, layout or working methods since the last test

The visit also needs to be planned safely. Some systems require access to high-level ducts, moving machinery or equipment containing hazardous residues. Site staff may need to arrange safe access, isolation or a permit to work.

What if there is no commissioning report?

The examination can still proceed, but the examiner has less information against which to compare current readings. They may use suitable manufacturer information, recognised guidance or other evidence to assess performance, and should explain the limitation in the report.

For an undocumented system, establishing a fuller performance baseline or producing commissioning information may require additional work. The absence of old paperwork should not be hidden behind a simple “passed” label.

2. What Does the Physical Examination Cover?

HSE describes the first stage as a thorough visual and structural examination. The examiner checks whether the LEV is in good repair, clean enough to operate properly and free from defects that could undermine extraction.

Depending on the system, this may include:

• Hoods and extraction points: position, condition, damage and obstructions
• Ducting and flexible hoses: leaks, splits, blockages, loose connections and build-up
• Fans and drives: damage, wear and signs of poor operation
• Filters and collectors: condition, fitting and filter-cleaning mechanisms
• Gauges, airflow indicators and alarms: whether they operate and give useful warnings
• Discharge and make-up air arrangements: issues that may affect the system’s performance

The exact checks depend on the equipment. A portable on-tool extractor, a multi-branch woodworking system and an enclosed spray booth will not have identical examination procedures.

3. What Airflow and Pressure Measurements Are Taken?

The examiner uses suitable instruments to assess the LEV’s technical performance. Measurements may include air velocity, volume flow rate and static pressure at relevant points in the system. The readings can help reveal a restricted duct, blocked filter, unbalanced branch, failing fan or hood that is not receiving enough airflow.

Where commissioning figures exist, current results should be compared with those original benchmarks. This shows whether performance has changed. The examiner also considers whether the original figures and system design are appropriate for the process now being carried out.

Not every test involves every possible instrument. The method should suit the hood, process, contaminant and system design. If a workplace has several extraction points, the examination needs to address their performance rather than relying on one reading taken beside the fan.

4. How Does the Examiner Check Whether the LEV Actually Works?

The third stage is to assess control effectiveness: is the dust, fume or vapour being captured, contained or intercepted before people breathe it in?

The examiner may observe the process in normal operation and use appropriate methods such as smoke, a dust lamp or other visual techniques to understand where the airborne contaminant goes. They may check whether a movable extraction arm is close enough to the work, whether an enclosure contains the contaminant and whether surrounding draughts affect capture.

Worker behaviour matters too. An extraction arm may perform well when positioned correctly but provide little protection if it is routinely pushed out of the way. The examination should reflect how the equipment is actually used, and the report should explain any operating changes needed.

Personal exposure monitoring or air sampling is a separate assessment that may be appropriate in some higher-risk circumstances. It is not automatically included in every LEV TExT.

5. What Should the LEV Test Report Tell You?

After the visit, you should receive a written report that lets you identify the system examined, understand its measured performance and act on any problems found.

A useful report should include, as applicable:

• The identity and location of the LEV system and the process it serves
• The date of examination and the conditions under which it was tested
• The parts and extraction points examined
• The tests and measurements taken, with relevant comparison figures
• An assessment of whether the system is controlling exposure effectively
• Defects, failed hoods or limitations in the examination
• Prioritised actions needed to restore or improve control
• The examiner’s details and the next examination requirement

HSE advises examiners to label tested hoods and use a clear fail label, or equivalent, for hoods that do not provide adequate control. A failed point should not be left looking available for normal use with the problem buried in a report.

Employers should keep LEV examination and test reports for at least five years and make them available where the system is used. The person responsible for health and safety and the person responsible for maintenance should both see the findings.

What Happens If the LEV Fails?

A failed or significantly defective extraction system needs action. The report should explain which part failed, why that matters and what needs to happen next. Depending on the fault, work could involve repositioning a hood, repairing ducting, replacing a filter, adjusting a damper, restoring fan performance or changing the working method.

The employer must decide how to prevent harmful exposure while the problem is being resolved. That may mean stopping the affected task, changing the process or using other suitable controls identified through the COSHH assessment. Once repairs or changes are complete, further testing may be needed to confirm that effective control has been restored.

A TExT identifies and documents the issue. It does not automatically include all the maintenance and remedial work required to put the system right. For that distinction, see our guide to LEV inspection versus maintenance.

How Can You Prepare for an LEV Examination?

Having the system and its records ready helps the examiner assess its real operating performance. Before the visit:

• Locate the commissioning report, previous test reports and logbook if available
• Identify every hood, branch or extraction unit that needs examining
• Explain any changes to machinery, substances or processes
• Arrange access to the equipment and suitable site supervision
• Plan for the relevant process to be demonstrated safely, where needed
• Explain known faults rather than waiting for the examiner to discover them

If records are missing, tell the provider when booking. They can then explain what can be established during the examination and whether additional baseline work may be necessary.

LEV Thorough Examination and Test FAQs

Is an LEV test just an airflow reading?

No. Airflow and pressure readings help assess technical performance, but an LEV TExT also examines the physical condition of the system and whether it effectively controls the contaminant during the work.

Does the machinery need to be running during the test?

The examiner may need to observe the normal process to judge capture or containment effectiveness. The precise arrangements depend on the equipment, hazard and safe system of work. Agree access and operating requirements before the visit.

Can LEV be tested without an original commissioning report?

Yes, but the missing baseline limits direct comparison with the system’s intended performance. The examiner should explain what information was used to reach a judgement and identify any further work needed to establish suitable benchmarks.

Does a passed LEV test mean no maintenance is needed?

No. Routine checking, cleaning and maintenance continue between statutory examinations. The report may also identify developing wear or actions needed before the next test.

Does a TExT include personal air monitoring?

Not automatically. The examiner may use visual methods and system measurements to assess control effectiveness. Personal exposure monitoring is a distinct assessment that may be needed where the risk and circumstances justify it.

What should I do if an extraction hood fails?

Review the examiner’s findings, prevent workers relying on ineffective extraction and arrange the required corrective work. The COSHH assessment should guide how the affected task is controlled until effective LEV performance is restored.

Sources and Further Guidance

• • HSE: HSG258 – Controlling airborne contaminants at work
  • HSE: Information for LEV designers, installers and examiners
  • HSE: LEV frequently asked questions
  • HSE: LEV commissioning and performance benchmarks