Ozone generators are sold for wiping out smoke, pet and mildew odors. The EPA’s position is clear, though: they are not safe air cleaners, and you should never run one where people or pets are breathing the air.
The one home use that makes sense is a short “shock treatment” of an empty space, following the maker’s instructions to the letter. Here’s what that involves, and when to call a professional instead.
What Is an Ozone Generator?
An ozone generator turns oxygen into ozone (O3), usually with an electrical charge (corona discharge) or UV light. Ozone is a strong oxidizer, so at high levels it can break down some odor molecules.
Those same high levels irritate the lungs. Ozone can cause coughing, chest tightness and shortness of breath, and it can make asthma worse.
Why the EPA Says They’re Not Air Cleaners
The EPA says ozone at levels safe to breathe does little to remove most indoor air pollutants, and no federal agency has approved these devices for use in occupied spaces. Running one around people doesn’t clean the air; it adds a lung irritant to it.
Ozone also reacts with chemicals already in the air and can form new irritants, such as formaldehyde. It doesn’t remove dust or pollen, and it won’t fix mold that’s still growing.
California limits the sale of ozone-emitting air cleaners for these reasons. For cleaner air day to day, a HEPA air purifier, an activated-carbon filter for odors and plenty of fresh air are the safe tools (see using an air purifier and humidifier together).
Scent only masks odors. A diffuser, even a homemade one like vanilla extract in a diffuser, covers a smell rather than removing it.
How to Use an Ozone Generator in the Home: Empty-Home Shock Treatment
If you decide to use one on a stubborn odor, treat it like a fumigation. Read the manual first and follow its run times, room-size limits and re-entry times, because those vary a lot between machines.
- Remove the odor source first. Clean or throw out smoky fabrics, pet-soaked carpet pad or moldy materials; ozone won’t fix a source that’s still there.
- Get everyone out. People, pets and houseplants all leave the treated area, and nobody goes back in, not even for a minute.
- Protect what ozone damages. High ozone can degrade rubber, some plastics, fabrics and artwork, so remove what you can and check the manual for anything else to take out.
- Seal off the area. Close windows and doors, and switch off the HVAC so ozone doesn’t spread to other rooms, unless the manual says otherwise.
- Use a timer. Let the built-in timer (or an outlet timer) shut the machine off, so you never have to walk in to unplug it.
- Wait it out. Stay out after it shuts off for at least as long as the manual says, often a few hours, while the ozone breaks back down into oxygen.
- Air it out. Open the windows and run fans to ventilate the space thoroughly before anyone returns. If you still smell a sharp, chlorine-like odor, keep airing it out (see how to get rid of ozone smell).
Anyone with asthma or another lung condition should stay away until the space is fully aired out. A dust mask or face mask does not filter ozone, so the only protection is staying out.
When to Call a Professional
For smoke damage after a fire, heavy cigarette smell through a whole house, or mold, a professional remediation company is usually the better choice. They can find and remove the source, and they use proper monitoring and safety gear.
For mold, the EPA advises fixing the moisture problem and cleaning or removing the moldy material. It suggests getting expert help when the mold covers more than about 10 square feet.
FAQs
How long should you run an ozone generator in a house?
Follow the manual, since run time depends on the machine’s output and the size of the space. Use the shortest time that works, and stay out until the re-entry time has passed and the space is aired out.
Can I use an ozone generator in my house?
Only for a short shock treatment of an empty space, never as an everyday air purifier. People, pets and plants must be out for the whole treatment and until the space has aired out.
How do I prepare my house for ozone treatment?
Clean up or remove the odor source, then get people, pets and plants out. Remove items ozone can damage, close up the area, switch off the HVAC unless the manual says otherwise, and set a timer.
How long can you be in a room with an ozone machine?
You shouldn’t be in the room at all while it’s running. Stay out until it has been off for the time the manual gives and the room has been aired out.
Conclusion
An ozone generator is a tool for treating an empty home, not an air purifier. Remove the odor source, follow the manual, keep everyone out and air the space out well, and call a pro for fire damage or mold.
Please be careful and use at your own risk
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