Thorough examination and testing (TExT) of local exhaust ventilation measures capture and face velocities, static pressures and overall condition against the system's commissioning performance. COSHH Regulation 9 requires this at least every 14 months.
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What LEV testing checks
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What air monitoring adds
LEV testing shows the system is moving air as designed; air monitoring shows whether worker exposure is actually below the limit. Only by combining the two can you be confident that the control is effective in practice.
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Using them together
Where exposure monitoring shows results approaching a limit, LEV testing helps diagnose why — a blocked filter, worn fan or poorly positioned hood. Together they form a complete, defensible control verification.
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Frequently asked questions
Is LEV testing the same as air monitoring?
No — LEV testing checks the extraction system; air monitoring measures worker exposure. Both are needed for full assurance.
How often must LEV be tested?
At least every 14 months for most systems under COSHH Regulation 9, and we test to HSG258.