Treatment effectiveness and safety are different

Using ozone for a technical or treatment purpose does not demonstrate that a space can remain occupied. Assessment needs to establish how it is generated, where it circulates, how it is removed and what happens on failure. Possible formation as a by-product must also be identified. A generator’s nominal output does not alone describe the concentration a person breathes.

Respiratory effects

NIOSH identifies eye and mucous membrane irritation and lung effects. ILO/WHO warns that significant inhalation can cause pulmonary oedema and that some effects can be delayed. Repeated exposure can affect the lungs. A significant incident triggers medical attention, without treating disappearance of the smell or initial improvement as proof of no harm.

Assessing exposure

Emissions, dispersion, ventilation and entry, operation and maintenance tasks are identified. Measurement requires a method appropriate for ozone and process conditions, with attention to interference and response time. A reading for another gas is not extrapolated. Results must be interpreted in relation to operations and the physical activity of exposed people.

Control generation and access

Unnecessary emissions are avoided, and those inherent to the process are contained or captured. Management of chemical agents must include alarms and access conditions where treatment may create a hazardous atmosphere. Re-entry needs verified technical criteria; simply waiting for a chosen time without knowing ventilation and residual concentration is insufficient.

Compatibility and maintenance

As an oxidiser, ozone can react with materials and substances present. Design must consider compatibility of equipment, pipework and exposed components, as well as possible reaction products. Maintenance verifies operation and leak tightness and considers supply or ventilation failures. Respiratory protection does not replace generator control or authorise work under unknown conditions.

Review example

In a hypothetical example, treatment equipment is installed in an area used by passing staff. Before use, gas circulation, access, ventilation and concentration verification are reviewed. A simple timer is prevented from being the only safety barrier. Verification includes failure scenarios because intended operation and an accidental release may require different responses.