Local exhaust ventilation is engineering control: it captures a contaminant at source before it reaches anyone's breathing zone. Because it is a control measure relied on under COSHH, it has to be maintained in efficient working order and it has to be examined and tested at intervals, by somebody who can tell whether it is still doing what it was designed to do rather than merely whether it is switched on.
What the law requires
COSHH regulation 9 requires engineering controls to be maintained in an efficient state, in efficient working order, in good repair and in a clean condition, and requires local exhaust ventilation plant to be thoroughly examined and tested at least once every 14 months, with shorter intervals for certain listed processes. Records of the examination must be kept for at least five years.
What a thorough examination and test actually covers
Not just airflow at the hood. A competent examination checks the system against its original design intent: hood position and shape relative to the source, capture velocity where the contaminant is generated, duct velocities to keep dust moving, filter and fan condition, discharge arrangements, make-up air, and whether the way the process is now run still matches what the hood was designed for. Processes drift, and hoods do not move with them.
Why so many systems fail on the paperwork rather than the fan
The commonest finding is a missing or lost commissioning record, so there is no design benchmark to test against. Without it the examiner can only report what the system does now, not whether that is what it should do. Keeping the user manual, the commissioning report and the log book together is worth more than any single test.
Where dust monitoring comes in
LEV testing measures the control. Personal exposure monitoring measures the person. They answer different questions, and a system that passes its test can still leave exposure above an exposure limit if the wrong contaminant is being captured or the operator works outside the capture zone. Occupational hygiene practice is to use both, with monitoring confirming that the control achieves what the assessment assumed.
What a good report leaves you with
A clear statement of whether the system provides adequate control, the measured values against the benchmark, photographs of hoods in use, a list of defects with priorities, and the date the next examination is due. A report that is a table of numbers with no verdict has moved the judgement back onto you.
Questions people ask about lev inspection
How often must LEV be tested?
At least once every 14 months under COSHH regulation 9, with shorter intervals for certain listed processes. Records must be kept for at least five years.
What is the difference between LEV testing and air monitoring?
LEV testing checks that the control equipment performs as designed. Air or personal exposure monitoring measures what a person is actually breathing. Both can be needed.
Who can carry out a LEV thorough examination?
A competent person with the knowledge and instruments to assess the system against its design intent. Professional qualifications in occupational hygiene or LEV examination are the usual evidence.
What if there is no commissioning record?
The examiner has no benchmark and can only report current performance. The practical fix is to have the system assessed and a benchmark established, then keep it with the log book.