Do Air Purifiers Produce Ozone? What Australians Need to Know

If you have been researching air purifiers, you have probably come across the warning that some of them produce ozone. It is a fair thing to check, and it is one of the questions we are asked most often before someone buys an Airdog.

The confusion comes from the fact that very different machines are all sold as air purifiers. This guide covers what ozone is, which technologies can produce it, what certification actually tells you, and where Airdog sits.

What exactly is ozone?

Ozone (O₃) is a gas made of three oxygen atoms. The oxygen we breathe has two. That extra atom makes ozone highly reactive, which is why it behaves so differently from ordinary oxygen.

Where it sits matters. High in the atmosphere, the ozone layer protects us from ultraviolet radiation. At ground level it is an air pollutant and the main ingredient in summer smog, which forms when sunlight drives reactions between nitrogen oxides and volatile organic compounds.

Breathing elevated levels of ozone can irritate the lining of the throat and lungs and make breathing harder. EPA Victoria notes that children, older people and people with lung conditions are the most sensitive. The US Environmental Protection Agency lists effects including coughing, throat irritation, chest pain, shortness of breath and aggravation of asthma.

One point is worth being clear about: ozone made by a machine indoors is the same gas as the ozone in outdoor smog. Terms such as "activated oxygen" or "energised oxygen" are marketing language, not a different, healthier form of the gas.

Why do people worry about ozone from air purifiers?

Because some products sold as air purifiers really do produce it.

Ozone generators release ozone into a room deliberately, on the theory that the gas will react with odours and pollutants. The US EPA has found that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants. California's air regulator has found that devices designed to produce ozone can push indoor concentrations well above health-based air quality standards, which is why they became regulated in the first place.

Other electronic purifiers, such as ionisers and electrostatic precipitators, are not designed to make ozone, but the high voltage they use to charge particles can create some as a by-product. How much depends heavily on how the product is built.

Put those together and you can see how "air purifiers produce ozone" became a blanket warning. It is sound advice about ozone generators. Applied to every purifier that uses electricity to charge particles, it is too blunt to help you choose.

Do all air purifiers produce ozone?

No. It depends on how the purifier works. Ozone generators produce it by design, while electronic purifiers vary depending on how the finished product is engineered and tested.

Here is how the main technologies compare.

Is Airdog an ozone generator?

No. Airdog does not use ozone to clean the air, and it is not designed to release ozone into your room.

An ozone generator's job is to put ozone into a space so the gas can act on odours and pollutants. Airdog's TPA® technology works on particles instead. It gives airborne particles an electrical charge inside the purifier, then collects them on washable plates within the unit. The cleaning happens inside the machine, not in the air around you.

That does place Airdog in the electronic air cleaner family, alongside other technologies that use an electric field. It is also why the more useful question is not whether a purifier uses electricity to charge particles. It is what comes out of the finished purifier, how much ozone has been measured, and whether the product has been independently tested and certified.

So, does Airdog produce any ozone?

Here is the straight answer. Airdog does not claim to be ozone-free, and we are not going to tell you it produces zero ozone. Like other electronic air cleaners, the charging stage in TPA® can create a very small amount of ozone as a by-product. What matters is how much leaves the finished purifier, and whether that has been checked independently.

Two things answer that for the Airdog X-Series.

What does CARB certification mean?

CARB is the California Air Resources Board, California's air quality regulator. Since 2010, every portable indoor air cleaner sold in California has had to be certified by CARB.

To be certified, an air cleaner must be tested for electrical safety. Electronic air cleaners, a category that covers ionisers, electrostatic precipitators and other technologies capable of generating ozone, must also be tested for ozone and meet an emission concentration limit of 0.050 parts per million (50 parts per billion). CARB publishes its list of certified models, so you can check a brand and model yourself.

What CARB certification does not tell you

CARB is clear about the limits of its own certification. It covers ozone emissions and electrical safety. It does not measure how well an air cleaner removes pollutants, and CARB states that certification does not imply a device is safe to use in a general sense. For cleaning performance, look at the clean air delivery rate (CADR) and the room size a model is designed for.

Why it is still worth looking for

CARB regulates products sold in California, but its certification is a useful reference wherever you live, because both the testing requirement and the list of certified models are public. If you are comparing ionising, electrostatic or plasma purifiers, look for that kind of evidence rather than taking a phrase like "ozone safe" on trust. Ask what the claim is based on: a named certification, a test standard, or a measured figure.

How does Airdog control what comes back into the room?

Airdog cleans the air in five stages, all of which happen inside the purifier.

1. Pre-filter screen. Air is drawn in from the bottom, and the pre-filter catches hair, pet dander and larger particles.
2. Wire frame. An electric field gives incoming particles an electrical charge.
3. Ionic field. The second part of the charging stage, before particles reach the plates.
4. Collecting plates. Charged particles are drawn onto the washable collecting plates and held inside the unit. Airdog's Help Centre states that charged particles are collected on the plates before air is returned to the room, rather than being released into your space.
5. Catalyst filter. The final stage, which Airdog describes as removing odours. If cooking smells and smoke are your main concern, see smoke and odours.

Cleaner air then returns to the room. The charging stage is the part of any electronic air cleaner that can create ozone as a by-product, which is exactly why the measured output of the finished unit, and its certification, are what count. It is also the process that captures ultrafine particles down to 0.0146 microns, with collecting plates you wash rather than replace. You can see the full TPA process here.

What should you check when buying any air purifier?

Whatever brand you are considering, these questions will tell you more than the claims on the box.

• Is it an ozone generator? If ozone is how it cleans, health agencies advise against using it in rooms people are occupying.
• Does it use ionisation, plasma or electrostatic technology? That is not a problem in itself, but it means ozone testing matters.
• Has the finished unit been tested for ozone? Testing the whole product counts for more than claims about one component.
• Is it certified, for example by CARB? Certification means the testing has been checked against a published limit.
• What is the measured emission? A published figure is more useful than a phrase like "ozone safe".
• What room size and CADR is it built for? An undersized purifier will not keep up, whatever technology it uses.
• What are the ongoing costs? Check what needs replacing, how often, and what it costs.
• Are the claims backed by evidence? Ask for the certification or test details behind them.

How Airdog answers those questions

Airdog and the usual assumption about ionisers

You will often read that ionisers are unsafe, full stop. It is easy to see where that comes from. Some ionisers release charged particles into the room so they settle on walls, floors and furnishings, and some designs have produced more ozone than anyone would want indoors. That is why Australian consumer advice often steers people with asthma away from purifiers that rely on ozone.

But the word "ioniser" covers very different designs. The US EPA describes ion generators that charge particles in a room so they are attracted to surfaces, and notes that some devices include a collector to draw charged particles back to the unit. Airdog's design charges and collects particles inside the purifier. Whether a particular product is a concern is not decided by the word on the box. It is decided by what the finished unit emits, measured against a recognised limit.

Warnings from health organisations are a good reason to ask questions, not a reason to stop at the label. They are exactly why emission limits, independent testing and certification exist, and why we publish ours.

Which Airdog is right for me?

Every X-Series model uses the same TPA® technology and carries the same ozone certification. The difference is the size of the room each one is built for.

X1D

Up to 10 m², CADR 100 m³/h

Bedrooms, nurseries and studies.

Buy X1D

Most popular

X3D

Up to 20 m², CADR 200 m³/h

Bedrooms, living rooms and home offices.

Buy X3D

X5D

Up to 35 m², CADR 350 m³/h

Open-plan living, dining and kitchens.

Buy X5D

X8D

Up to 100 m², CADR 800 m³/h

Large homes and busy shared spaces.

Buy X8D

Every X-Series model: patented TPA® technology, washable collecting plates, CARB-certified, and a published ozone specification of 0.01 ppm (10 ppb) or less.

Frequently asked questions

More technical answers are in the Help Centre. If allergies or hay fever are your main concern, see allergies and hay fever; for asthma, see air quality and asthma; for nurseries, see babies and nurseries; and for homes with animals, see pets and pet dander.