Ozone glossary — key terms explained

A clear, jargon-free guide to the terms you will come across when treating odours with ozone. Each entry gives a one-line definition followed by a fuller, accurate explanation — written for real-world use, not marketing.

Ozone (O₃): A reactive gas made of three oxygen atoms. Ozone is a naturally occurring gas whose molecule consists of three oxygen atoms instead of the two found in the oxygen we breathe (O₂). Because that third atom is loosely bound, ozone is highly reactive and breaks down readily, which is what allows it to neutralise odour molecules. Generated on demand from the surrounding air, it is used indoors for short, room-empty treatments only.
Oxidation: The chemical reaction by which ozone neutralises odours. Oxidation is the process in which ozone gives up its reactive oxygen atom to other molecules. When that happens to the volatile compounds responsible for smells — from smoke and cooking to damp and pets — their structure is altered so they no longer register as an odour. This is a chemical change, not masking, which is why the result lasts once the room has been aired.
mg/h (milligrams per hour): The standard measure of an ozone generator's output. Output is rated in milligrams of ozone produced per hour (mg/h). A higher figure means more ozone delivered into the air over the same period, so larger or more heavily affected spaces need a higher rating. Matching the output and run time to the room volume is the key to an effective treatment without overdosing the space.
Oxion™: Our combined ozone, active-oxygen flow and ionisation technology. Oxion™ is the technology in the Oxia range that pairs ozone generation with an active-oxygen flow and air ionisation. The aim is faster, more even distribution of treatment through a room and improved freshness of the air. It is designed for odour remediation in empty rooms, after which the space is ventilated before re-entry.
Half-life: How long it takes ozone to decay to half its concentration. Ozone is unstable and converts back into ordinary oxygen over time. Indoors, its half-life is typically around 20–30 minutes, depending on temperature, humidity and surfaces present. This self-decay is a safety feature: it means a treated room returns to normal air on its own, and airing the space simply speeds the process.
Ground-level ozone: Outdoor ozone formed by pollution and sunlight. Ground-level (tropospheric) ozone is the ozone found in outdoor air, formed when sunlight reacts with traffic and industrial emissions. It is the ozone referred to in air-quality warnings and is distinct from the controlled, on-demand ozone used briefly inside an empty room for odour treatment. Understanding the difference helps explain why outdoor exposure and indoor treatment are handled so differently.
CT value (concentration × time): Concentration multiplied by exposure time. The CT value combines the concentration of ozone with how long it is present, because both determine the overall effect of a treatment. In practice it explains why a lower output run for longer can achieve a similar result to a shorter, stronger burst. It is also the principle behind keeping rooms empty during treatment and airing them out afterwards.
Odour remediation: Removing the source of a smell rather than covering it. Odour remediation means dealing with the molecules that cause a smell so the odour does not return, as opposed to air fresheners that simply mask it. Ozone achieves this by oxidising those molecules during a room-empty treatment. It is well suited to lingering smells such as smoke, damp, cooking and pet odours that have settled into a space.
Off-gassing / VOCs: Smelly volatile compounds released by materials. Volatile organic compounds (VOCs) are carbon-based chemicals that evaporate easily from materials such as new furnishings, paints and soft fittings, and are a common source of indoor odours. The slow release of these compounds is known as off-gassing. Many odour-causing VOCs can be neutralised through oxidation, which is why ozone treatment is used to freshen spaces affected by them.
Ventilation: Airing a room to clear residual ozone after treatment. Ventilation is the deliberate exchange of indoor air with fresh outdoor air. After an ozone treatment, opening windows and doors for at least 30 minutes clears any remaining ozone and speeds its natural decay back to oxygen. Proper ventilation before re-entry is an essential part of safe, effective use.

Definitions are written to align with guidance from public authorities including the US EPA, UK HSE and the WHO.

Shop ozone generators