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LEV testing - the wider duty
Testing your extraction proves the control is working. It says nothing about whether anyone has already been harmed. Those are two different questions, and COSHH asks both - which is why passing one duty never discharges the other.
The short answer
LEV testing and health surveillance are separate duties under COSHH that answer different questions. A thorough examination and test checks that the extraction is controlling exposure. Health surveillance checks whether the people exposed are staying healthy. A passing LEV test does not remove the need for surveillance, and surveillance does not remove the need to test - where the risk calls for both, you owe both.
Duty one
The thorough examination and test is about the engineering. It measures whether the local exhaust ventilation is capturing the contaminant at source and controlling exposure, and it is required at least every 14 months under COSHH Regulation 9. Its subject is the system - the hoods, ducts, fan and filters - and its output is a report saying whether the control does its job.
That is a vital duty, but it has a blind spot by design: it tells you about the equipment, not about the person standing at it. A system can pass its test and still, through a lapse before the test or a use it was never designed for, have let someone be exposed. Testing the control cannot see that. Something has to look at the worker.
Duty two
Health surveillance is the other half. Where employees are exposed to substances that can cause identifiable ill health - respiratory sensitisers, certain dusts and fumes, isocyanates and more - COSHH can require ongoing health checks to catch early signs of harm before they become serious or permanent. For isocyanate exposure, for instance, health surveillance is mandatory.
Its subject is the person, not the plant. Lung function tests, skin checks, questionnaires and the records that go with them are looking for the first indications that control has not been good enough - the evidence a machine reading cannot give. It is an early-warning system for the human cost that a passing LEV test can mask.
Why one does not cover the other
The two duties catch different failures. LEV testing catches a control that has degraded - a hood under-capturing, a filter spent - before it harms anyone, ideally. Health surveillance catches harm that is already occurring despite the control, whether because the system was inadequate between tests, used wrongly, or simply not enough for the exposure. Neither can do the other's job.
So treating a clean LEV certificate as evidence that no one is being harmed is a mistake, and so is relying on health checks while neglecting the extraction that should prevent the harm in the first place. The point of control is to stop exposure; the point of surveillance is to prove, worker by worker, that it worked. You need both readings to know where you stand.
How they work together
In practice the two duties feed one another. A health surveillance result that shows early harm is a signal to look hard at the LEV, even if it recently passed - the control may be adequate on paper but failing in use. Equally, an LEV test that finds under-performance is a prompt to check whether anyone exposed in the meantime needs surveillance attention.
Run together, they close the loop between the equipment and the people it protects. The test keeps the control honest; the surveillance keeps the test honest, by checking that the control is actually keeping people well. Managed as a pair, they give a far truer picture than either alone.
What you owe
What you actually owe is set by your COSHH risk assessment. It identifies the hazardous substances, the exposure, and the controls - and from that flows both the LEV testing regime and whether health surveillance is required, and how often. The duties are not optional add-ons; they are the assessed response to a real risk.
The practical takeaway is to treat them as a set. Keep the LEV examined and maintained on its cycle, keep the health surveillance running where the risk calls for it, and keep the records for both. Doing one well while neglecting the other leaves a gap exactly where COSHH expects you to be covered - between a working control and a protected workforce.
Questions
No. LEV testing checks that the extraction is controlling exposure; health surveillance checks whether the exposed workers are staying healthy. They are separate COSHH duties answering different questions.
No. A test proves the equipment works, not that no one has been harmed. Where the risk requires health surveillance, it is still owed regardless of the LEV result.
Where employees are exposed to substances that can cause identifiable ill health - certain dusts, fumes and sensitisers. For isocyanate exposure, for example, health surveillance is mandatory. Your COSHH risk assessment determines it.
Each informs the other. Early harm found by surveillance is a signal to re-check the LEV; under-performance found by testing is a prompt to check whether exposed workers need surveillance attention.
Your COSHH risk assessment. It identifies the substances, exposure and controls, and from that flows both the LEV testing regime and whether health surveillance is required and how often.
Both the LEV thorough examination and test reports and the health surveillance records, each kept for the periods COSHH requires, so both halves of the duty can be evidenced.
We test your extraction to COSHH and HSG258 - the essential first half of protecting the people who rely on it.
