Local Exhaust Ventilation (LEV) Assessment

Under COSHH Regulation 10, employers must monitor exposure to hazardous substances where it is needed to protect health, where a workplace exposure limit could be exceeded, or where control measures need to be verified. LEV performance monitoring provides the objective evidence that satisfies this duty.

Uncontrolled exposure to LEV performance is linked to occupational disease where extraction fails to control exposure. Beyond the legal duty, robust monitoring protects your workforce, reduces the risk of enforcement action and civil claims, and gives insurers and clients confidence that exposure is being actively managed.

We measure exposure using measurement of capture velocity, face velocity, static pressures and qualitative checks, with supporting air monitoring, following the recognised COSHH Reg 9 / HSG258 methodology. Personal samplers are worn in the breathing zone for a representative full shift to derive an 8-hour time-weighted average, while static (background) samples help map contaminant sources across the workplace.

Samples are analysed by an accredited laboratory and the results compared with the relevant occupational exposure limit. Where short-term peaks are a concern we add 15-minute short-term exposure limit (STEL) sampling, so both the chronic and acute risk picture is captured.

The current workplace exposure limit for LEV performance is TExT at least every 14 months (EH40/2005, as amended). We assess compliance using the BS EN 689 statistical decision framework, which accounts for exposure variability rather than relying on a single result.

Your report sets out the measured concentrations, the compliance position, the adequacy of existing controls such as local exhaust ventilation, and a recommended re-monitoring interval. It is written to be understood by managers and to satisfy HSE inspectors, auditors and insurers.