Ozone is a hazardous gas. Professional use starts with eliminating or preventing exposure, not with selecting a timer or relying on odour as an indicator.
This guide describes general control principles. It is not an operating procedure, risk assessment or clearance certificate. The duty holder must obtain competent, site-specific advice and apply current requirements.
Assess the actual risk
COSHH assessments should identify who might be exposed, how exposure could occur, what controls are needed and how they will be checked. Consider workers, contractors, visitors and anyone who could enter the boundary unexpectedly.
Prevent access and control generation
Define the treatment boundary, secure access, communicate the hazard and establish what conditions permit generation. Where controls are integrated with ventilation, the design should make loss of proving or a relevant fault lead to a defined safe state.
- Controlled access and visible warning arrangements
- Defined enable conditions and fault response
- Safe shutdown and emergency response
- Clear responsibility for setup and release
Use monitoring as part of a method, not a ritual
Where the assessment requires monitoring, select a suitable maintained instrument, define where and when measurements are taken, understand its range and limitations, and record the decision. A timer, smell or assumed decay period is not by itself a verified clearance decision.
Release only on a defined basis
The competent person responsible for the work should define the purge, ventilation, measurement and release sequence before treatment. Workplace exposure limits are occupational benchmarks; do not automatically treat them as public-access or re-entry rules for every scenario.
Authoritative sources
External sources are provided for context. Check the current editions and apply them to the actual site, equipment and duty.