IS OZONE
TREATMENT SAFE
FOR YOUR HOME?

Why Ozone Requires Caution During Treatment

Ozone (O₃) is effective at eliminating odour because it is chemically reactive — it oxidises and permanently alters the molecules it contacts. This same reactivity makes it potentially harmful to the human respiratory system and to other living organisms at the concentrations used in professional treatment.

At high concentrations, ozone causes irritation of the airways, coughing, shortness of breath and, with prolonged exposure, can cause more serious respiratory effects. This is why professional treatment concentrations are far above the safe occupational exposure limit of 0.05 ppm (parts per million) set by the UK Health and Safety Executive, and why the property must be completely vacated during treatment.

The key point: ozone at professional treatment concentrations is not safe to breathe. But ozone fully decomposes back into ordinary oxygen given time and ventilation. Once concentration has returned to safe levels, the treated property is completely safe to re-enter — and the ozone leaves no chemical residue.

Who and What Must Vacate

Before treatment begins, the following must be removed from the property:

• All people — including infants, children, elderly and anyone with respiratory conditions. Nobody may enter the property during treatment under any circumstances.
• All pets — including dogs, cats, birds, fish, reptiles, small mammals and invertebrates. Fish tanks and aquaria must be removed or sealed with the pump disconnected; even brief exposure to ozone at treatment concentrations is fatal to fish.
• All plants — ozone damages plant cell walls and will kill or severely damage any plants left in the treated space.
• Open food — any food not in airtight sealed containers should be removed. Sealed, airtight containers are acceptable to leave.

Materials to Protect or Remove

Ozone at high concentrations can affect some materials. We will advise on this during the site assessment, but as a general guide:

• Natural rubber and latex: Ozone degrades rubber over time. Remove or cover rubber items where possible.
• Some artworks and photographs: High-value or fragile artworks should be removed or sealed in acid-free bags.
• Leather goods: Prolonged exposure to high ozone concentrations can affect leather. Remove valuable leather items where practical.
• Electronics: Standard consumer electronics are generally unaffected by short-duration professional treatment. We will advise if any specific concern arises during assessment.

Why Professional Monitoring Matters

All Ozone London treatments include real-time O₃ concentration monitoring using calibrated sensors throughout the property. This serves two purposes:

• Treatment effectiveness: Monitoring confirms that effective treatment concentrations have been reached and maintained in every room for sufficient time. Without this, you cannot know whether treatment was actually effective.
• Safe re-entry: Monitoring confirms that ozone has fully dispersed to safe levels before anyone re-enters. We do not estimate or rely on timing alone.

Consumer ozone machines have no monitoring capability. Users have no way to verify what concentration was reached or whether it has fully dispersed before re-entry.

Safe Re-entry Times

After treatment ends, ozone disperses naturally as it decomposes back into oxygen. Ventilation accelerates this. Typical re-entry times for a well-ventilated property:

• Studio or 1-bed flat: typically 1–3 hours after treatment ends
• 2–3 bed flat or house: typically 2–4 hours after treatment ends
• Larger properties: typically 3–6 hours after treatment ends

These are guidelines only. We confirm the safe re-entry time for your specific property based on monitored readings — not estimates.

What to Expect After Treatment

Once you re-enter, the property should smell neutral or very faintly of the characteristic clean, slightly metallic smell of ozone that dissipates within an hour or two. There is no chemical residue from the ozone itself — it fully breaks down into oxygen.

We recommend ventilating the property for 30–60 minutes on re-entry. After this, the property is fully safe for normal occupation.

The Risk of Consumer Ozone Machines

Consumer ozone generators present safety risks that professional treatment does not, because they lack monitoring. Users frequently underestimate dispersal times, re-enter too soon, or — in the most dangerous cases — run machines while occupied, which can cause acute respiratory effects. If you use a consumer machine, ensure you fully vacate, do not re-enter for at least the manufacturer’s minimum recommended time (typically 2–4 hours), and ventilate before returning.