Quick answer
Local exhaust ventilation should capture the relevant airborne contaminant at or near its source and remain effective during actual work. Use competent design/commissioning, clear user checks, maintenance and required examination/test arrangements. A fan running or air movement felt by hand is not proof that the system controls exposure.
Define the contaminant and control purpose
HSE LEV guidance explains how performance information and checks support reliable control. Identify the source, task, substance and working conditions before selecting or changing equipment.
A general room fan, comfort ventilation and a COSHH control system do not automatically have identical purposes or examination requirements. Establish what the installed system is intended to control and the evidence supporting it.
Give users practical checks and limits
| Check | What staff need to know |
|---|---|
| Setup | The approved hood/source position and operating arrangement. |
| Performance indication | How to recognise the defined acceptable indication. |
| Condition | Damage, blockage, leaks or changed equipment. |
| Use | How work must remain within the approved capture arrangement. |
| Failure | When to stop the affected task and who to contact. |
Do not set universal airflow or capture-velocity numbers from a generic article. The appropriate evidence depends on the process and design.
Arrange competent examination and records
For GB COSHH LEV, the general maximum interval for thorough examination/test is 14 months, with shorter intervals for specified processes and more frequent attention where needed. User checks and maintenance are separate; a future test date does not authorise use of a failed system today.
HSENI guidance gives the NI framework and relevant interval qualifications. Check the actual statutory schedule and process with a competent examiner. Keep the necessary report and design/commissioning information; HSE identifies at least five years for examination records.
Assess changes before relying on the old report
Illustrative example: production moves the capture point or changes the powder-handling task. The old performance report may no longer describe the actual use. Obtain competent review and necessary recommissioning/evidence before assuming control.
After a fault, use the approved stop/alternative-work procedure. Do not improvise a dust mask, bypass an alarm or modify ducts to keep production running.
Verify the control in actual work
Check that the examiner understands the process and can assess intended performance, not just provide an airflow number. Follow up defects and verify authorised return to use. Review staff understanding and recurring failures.
For cooking-fume systems, coordinate the exposure assessment with separate gas/appliance and other safety requirements. The presence of a canopy does not establish that every relevant hazard is adequately controlled.
Next steps
- Define the actual contaminant/task and competent control design.
- Train users in setup, checks and failure response.
- Maintain and examine/test at the applicable intervals.
- Review changes and verify effective return to use.
Read the official practical guidance — Use the current source alongside the procedures for your own business.