Which Air Purifiers Produce Ozone And Which Do Not?

It is no secret that not all air purifiers will give off ozone. Some purist models output 100% mechanical HEPA filtration, while some emit a safe ozone concentration level byproducts via UV or ionization. In the midst of the marketing fog, the trick is to identify which is which based on the specification. We will guide you to the best air purifiers that don't produce ozone and avoid those that no one should touch. Read on.
Short answer
Not all air purifiers give off ozone.


Ozone (O3) is a highly reactive gas formed of three oxygen atoms. It is created naturally in the upper atmosphere (stratosphere) to shield us from harmful UV rays. However, ozone can also be artificially made through devices, notoriously ozone generators. Ground-level ozone is dangerous to living organisms in the earth’s lower atmosphere (troposphere). According to the American Lung Association (ALA), excessive exposure can cause breathing problems, coughing, shortness of breath, chest pain, wheezing, blurry vision, memory loss, and aggravating asthma symptoms. In the long run, ozone can inflame the lining of the respiratory system and permanently damage lung cells, resulting in lung capacity deterioration.

There is scientific evidence that ozone does not remove particles from the air and is ineffective against odor. It also reacts with existing airborne chemicals like formaldehyde to form additional toxic pollutants. Ozone will chemically react with other smog pollutants like nitrogen oxides (NOx) from vehicle emissions and volatile organic compounds (VOCs) found in many industrial products. It can damage and break down rubber into dust powder. Ozone is known to deaden one’s sense of smell, which can be dangerous as it decreases a person’s ability to detect toxic vapor. Many health organizations, including EPA and WHO, categorized ozone as an air pollutant.

How To Pick An Air Purifier That Does Not Produce Ozone?

Unlike an ionizing air purifier that emits ozone from the electric charge, there’s no ozone emission from air purifiers that use only mechanical filtration like a HEPA filter. If you are looking for a 100% ozone-free air cleaner, it should consist of HEPA filtration as such:

  • Pre-filter – A washable filter that traps visible, large particles like dust, debris, lint, and fiber. It will protect the HEPA and carbon filter from being damaged or clogged with large particulates.
  • HEPA filter – Remove 99.97% of microscopic particles as small as 0.3 microns like dust mite, pet dander, mold, pollen, bacteria, and viruses without producing any ozone. A must-have filtration.
  • Activated carbon filter – Neutralize odor and gaseous pollutants from cooking, pets, cigarette, VOCs, carbon monoxide, carbon dioxide, radon, and formaldehyde. The perfect ozone-less partner to complement a HEPA filter.

There is also advanced PECO technology made famous by the Molekule air purifier. An improved version of PCO in terms of efficiency and safeness. PECO uses UV-A light rather than UV-C, producing less to nil ozone during purification. Some studies show that the Photo Electrochemical Oxidation process can even convert ozone into oxygen molecules. However, it is a reasonably new technology compared with the many decades-old HEPA filters. Take it as a pinch of salt.

Which Air Purifiers Emit Ozone?

BrandProduce Ozone?It There Ozone Generators In The Lineup?Is It Safe For Home Use?
Austin Air PurifiersNONOYES
NuWave Oxypure Air PurifiersINSIGNIFICANTNOYES
Hamilton Beach Air PurifiersSOME (INSIGNIFICANT)NOYES
Sharper Image Air PurifiersINSIGNIFICANTNOYES
Dyson Air PurifiersNONOYES
IQAir Air PurifiersNONOYES
New Comfort OzonatorsYESYESNO
Airthereal OzonatorsYESYESNO
Enerzen OzonatorsYESYESNO
OdorStop OzonatorsYESYESNO

Below are our handpicked HEPA air purifiers that are 100% ozone-free and safe for everyday use.

  1. Winix 5500-2
  2. Coway Airmega 300
  3. Honeywell HPA300
  4. Medify Air MA-15
  5. IQAir HealthPro Plus
  6. LEVOIT Core 300

Visit our best ozone-free air purifier page to see the full specification and reviews.

Ozone-free Air Purifiers

Types Of Air Purifiers With Ozone Output

Not all air cleaning technologies are created equal. Some do produce ozone even though it is at a neglectable level. If you are aiming for an ozone-free model, below are a few air cleaners that you need to watch out for.

  • Ozonator/ Ozone generator – While technically not an air purifier as it does not clean the air, Ozonator is often masked as one because it is more approachable and sellable. In actual fact, it releases a high concentration of harmful ozone that brings no benefit to your health. Most home ozone generators emit dangerous levels of ozone higher than the State’s outdoor 1-hr 90 ppb and 8-hr 70 ppb health standards. Commercial ozone generators emit higher than 5,000 mg of ozone hourly. At this moment, no government agency has the authority to regulate these devices extensively. Stay away from one.
  • Ionizer/ Negative ion generator – A popular technology commonly found as a standalone or part of a multi-level filtration. An ionizer uses a corona discharge to release charge ions and attach them to other particles in the air. The merged particles will fall on the sofa, bed, wall, cabinet, curtain, or any surface area as the added weight makes it impossible to remain suspended in the air. It is safe for home use as the outputted ozone is within the CARB emission limit.
  • Electrostatic Precipitation – A dedicated device that works like an ionizer with an additional charged plate/ rod to attract the fallen particles in the air. Its effectiveness is somewhat restricted as there is just so much the charged plated can pull in before requiring cleaning. Some byproducts will also be produced, where oxygen molecules will be broken apart and converted into ozone momentary.
  • UVGI/ UV air purifier – Uses UV-C light radiation to kill microorganisms like mold, bacteria, and viruses pulled inside the chamber. While there is not much of a risk of radiation exposure, oxygens molecules will break apart and form ozone at a very low concentration level. As ultraviolet light can be primary or part of a multi-filtration, its effectiveness is highly dependent on the UV light intensity and the duration of the exposure. It should not be the direct replacement of mechanical, filter-based filtration.
  • PCO air purifier – Through Photocatalytic oxidation, the combination of chemical catalyst coated filter and UV lamp produces hydroxyl radicals that break down chemicals into CO2/ water. While the effectiveness is debatable, compounds like formaldehyde, radon, nitrogen dioxide, and ozone byproducts might react differently or combine with other compounds to form new toxic gas. This should not be on your consideration list if there is any ozone concern.
Ozone Generators

What To Do If You Have An Air Purifier That Produces Ozone

Please don’t fret, as it might not be as bad as it seems. Here are a few things you could do to ensure the air purifier is still workable.

  • Make sure it is not an ozone generator – Many Ozonators are often labeled as an air cleaner or ionizer to trick users into getting one. Do a quick google search to check on the specification and certification. If is CARB approved to be ozone-safe, double confirm it on the California Air Resources Board website.
  • Turn off the optional ionization or UV-light – This step only applies to a HEPA air purifier with multi-stage filtration. While the ozone emission level is at a very low concentration level, you can switch it off at any point of the purification. The primary mechanical filtration will still be functional to capture airborne pollutants in the air.
  • Do not use it in a tiny, enclosed area – If your air purifiers produce some light ozone byproducts, it is best to use it in a bigger room so the byproducts will spread out rather than lingering concentrated in one place. As such, placing the air purifier in the living room would be preferable over a small bedroom. Remember to keep all windows closed to prevent clean air from escaping.
  • Use it when nobody is around – If you are worried about the ozone byproducts created from an air ionizer, try running it at max speed with a timer when no one is present in the room. The ozone gas will disperse quickly before anyone steps foot in the room.
  • Vacuum and clean frequently to prevent dust particles and mold build-up.
  • Keep smoke away from home. Only smoke outdoor and reduce and usage of gas or wood-burning appliances.
  • Purchase or replace building materials and wood furniture that do not emit formaldehyde.

Ozone Generators VS Ionizers (Not The Same)

An air ionizer, AKA Ionic air purifier, is not the same as an ozone generator. An ionizer diffuses negative ions to clean the air; however, the electric charge produces insignificant ozone byproducts. Most ionic air purifiers in the market are CARB and EPA compliant with standard ozone output not more than 0.070 ppm (parts per billion). On the other hand, ozone generator deliberately produces ozone to "clean" the air. According to The Nizkorodov study funded by the National Science Foundation, ozone is ineffective in destroying biological pollutants and large particles like dust. You will need an unsafe concentration level of ozone to do so. The ozone emission can quickly build up matching outdoor pollution smog levels, especially in an enclosed area like a bathroom. Worse still, the ozone will take days to dissipate or air them out. It is dangerous and can do more harm than good to our health.

All ozone generators exceeded California defined ozone emission limit and are banned from sale. Unfortunately, most ozone generators are not regulated in other states and still can be purchased by the public.

Some home appliances produce minimal ozone byproducts that are still safe for use. The printer is a prime example that can be found in most households. You do not have to stop using it as the amount of ozone created is insignificant and will not cause an alarm.

How Do I Know If My Air Purifier Produces Ozone?

You can find the ozone emission level on the manufacturer's information manual, box set, and official website. Note that the ozone emission data have restricted use as most manufacturers do not reveal the standard used for ozone assessment. To reduce ozone exposure risk, go with a reputable brand, complete mechanical filtration, and avoid using the air cleaner in a small enclosed area.

Do All Ionizers Produce Ozone? Is Breathing Ionized Air Safe?

Yes, they all do. Ionizers create negative charged ions and will emit minimal ozone byproduct of the molecular reaction. Inhaling or exposure to negative ions is safe for humans. It is similar to naturally occurring sunlight, thunderstorm, and waterfalls. It is the ozone that poses a risk to human health.





Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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