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The Complete Ozone Generator Guide | Air Purifier RatingsAir Purifier Ratings

The Complete Guide to Ozone Generators For Air Purification

As you read through our site you will see we focus on testing air purifiers.  One type that we have not tested is the ozone generator.

We want to see what works and how it can help you.  For the removal of particles this is done with a particle counter.

One area where we are not able to test is for ozone.  In a sense this not a big deal since air purifiers are certified to meet certain ozone requirements.

Yet, we see a class of air purifiers that exist to produce ozone – the ozone generator.

And this got us thinking.  How could a class of air purifiers have the sole function of creating ozone?

The EPA says “NO agency of the federal government has approved these devices for use in occupied spaces.”

Ozone is a key component of smog.  And why certain parts of the country issue ozone action days to limit physical activity.

So why would anyone buy an ozone machine?  Essentially a smog machine.

What is an ozone generator used for?

The main purpose of an ozone generator is to remove odors.

This is done in a different way than carbon.  Carbon absorbs the gases and holds them in its tiny crevices.

Ozone is O3.  It has an extra oxygen atom.  It is unstable and quick to chemically react with gas molecules it comes in contact with.  This has a strong oxidative effect that works well to remove some odors.

ozone generator atom

With carbon filters, odors are removed by catching them as they pass through the air purifier.

In contrast, nothing passes through the ozone generator.  Rather, it emits ozone into the room where it reacts with the odors.  So, ozone molecules are sent out into the room to change the chemical structure of the odor.

It’s like sending out an army to battle the odors.  To be effective it needs either a high concentration or longer contact time in the room.

How do you create ozone?

Ozone is created in a few different ways.  Most ozone generators use the Corona Discharge method.

We won’t go into the details here but simply it is an electrical charge from the ionization of the air.  This electrical charge converts O2 to O3 from a high powered ionizer.

Isn’t ozone good?

Ozone in the upper atmosphere is good as it reduces the amount of ultraviolet radiation from the sun.  It helps to protect us.  It’s like a barrier between us and the sun.

But there is a distinction when it comes to the air we breathe.   Ozone is not meant to be breathed in.  It is considered ground level air pollution.

We will go into why it’s a problem.

Ozone generator dangers

We have read through every bit of research we can find about ozone.  In all this information we have not come across any credible source that suggests ozone is good.  Rather, it comes with many cautions.

The closest analogy I can think of is it’s like fumigating your home with dangerous chemicals.  It can be effective for pest removal but you surely don’t want to be around when it’s done.  You would never want to buy one of these to clean the air in your home while you are around.

One reason is because ozone attacks your lungs.  It causes decreased lung function, severe asthma symptoms, shortness of breath and chest pain.  It also causes throat irritation and cough.

Here is a short video from the EPA.

What we listed above are the immediate health effects of ozone.

But, the bigger concern is the short and longer term exposure.  The EPA and American Lung Association report ozone is likely to cause early death.  Harm to the cardiovascular system can result in heart attacks, strokes, heart disease, etc.

It’s not something to be taken lightly.

And not just to us.  If you have pets they will be breathing in the same air.

Furthermore, ozone in combination with other chemicals can create harmful by-products like formaldehyde.

The Canadian Center for Occupation Safety and Health states:

“Even very low concentrations of ozone can be harmful to the upper respiratory tract and the lungs.”

The California Air Resources Board sums it up by saying.  “Avoid using products that emit ozone intentionally (ozone generators).”

How effective is ozone?

From what we have seen ozone can be quite effective at smoke removal.  It has the ability to touch smoke odors in carpeting, walls – pretty much everywhere.

However, it is not effective for all odors.

And requires high concentrations.  The EPA has reported that at safe ozone levels: “ozone is not effective at removing many odor-causing chemicals.”

They go on to say it’s not effective for particle removal either.

From this research report it seems the chemical reaction process could take months.

If you need dust or allergy relief, ozone will not help as there is no effect on the removal of particles.  Dust, pollen, pet dander, mold spores, etc are particles.  They are not removed by the introduction of ozone into your room.  The best way to remove them is with a HEPA filter.

An extra word of caution

It is difficult to know the actual ozone concentration levels from an ozone machine.  This is because ozone generators produce varying levels of ozone.

Room size is also a consideration.  Smaller sq ft sized rooms will reach a high concentration more quickly.

How well ventilated the room is also factors in.  Mixing in air from the outside or an adjoining room will affect the ozone concentration.

You also need to consider what is in the room with the ozone generator.  Ozone will react with other chemicals.  And not always in a good way.  If you have cleaning chemicals for example, there could be dangerous chemicals produced as a by-product.  There are also chemicals in off-gasing from carpeting and some wood.

Negative ionizers

A negative ionizer is a device that emits a negative charge.  The purpose is to improve the indoor air quality by making it easier for a HEPA filter to catch the particles.

But what about ozone production?

If you are buying a room air purifier and it has a negative ionizer chances are that it is within the ozone limits.  The standard is less than 0.05 ppm.

The State of California maintains a listing of certified air purifiers for ozone.  Here is a picture of their website.

certified ozone air purifiers

What is nice about this list is that they also show the type of air purifier for each certified model.  The types are listed as mechanical or other.  Mechanical means it just uses HEPA and/or carbon filters.  Nothing that could potentially produce ozone.  “Other” means it uses an ionizer, uv, or some other electrical technology.

In our testing we see most air purifiers have an ionizer.  In reading through customer reviews we found some like this feature while others do not.

For example, we have seen reviews from bird owners concerned about any possible ozone even if it is considered safe.  While this seems to represent a small percentage of reviews it is something to consider.

What we have seen is that some air purifiers allow you to turn off the ionizer while some do not give you this option.

If you are not sure you may want to go with a mechanical air purifier or one with the option to turn the ionizer off.

Ozone Alternatives

Air purifiers sold to consumers in California are certified to operate within safe ozone limits.  Since California is such an influential state this has in a way set a national standard.  As a result an ozone generator is now sold as a commercial product.  From what we can see it is not a consumer product.

But there are other options.

If you want to safely remove odors, the best way is with an activated carbon filter.  Carbon will not introduce pollution into your home and will give your home clean fresh air.  In this article we go into some details for what to look for.  Activated carbon is not good for all odors but does a decent job with smoke odors and general odors.


In this article we looked at the ozone generator.  Where you would use one, what they are good for and what you need to watch out for.

We focused much attention on the safety and health aspects.

This product is more of a commercial air purifier that is used by professionals since ozone is considered indoor air pollution and causes lung damage.  Everything we have read indicates you do not want to be around when an ozone machine is run or has been run.