Ozone Generators: How Does An Ozone Machine Work? (+Safety Concerns)

“When inhaled, ozone can damage the lungs. Relatively low amounts of ozone can cause chest pain, coughing, shortness of breath and, throat irritation.” (EPA on ‘Ozone Generators that are Sold as Air Cleaners’)

We all know the ozone layer. It’s the protecting shield in the Earth’s stratosphere. That’s the good ozone.

What is the ‘bad’ ozone EPA specifically warns about?

According to the EPA, if we were to breathe in ozone, it might damage our lungs.

Here’s the deal:

There’s a whole lot of ozone generators manufacturers are selling as “air purifiers”. Undoubtedly, ozone, an “active oxygen” O3 seems to destroy a range of air pollutants, even bacteria, and viruses.

ozone generators influence of indoor air quality
Air purifiers are designed to remove air pollutants and increase indoor air quality.

However, on the other hand, it’s harmful to our health. Why would anybody use an ozone machine in their homes? As EPA warns, it seems that ozonators, machines that use ozone generation to destroy air pollutants, produce more health concerns than air purification benefits.

In this article about ozone air purifiers, we will look at what ozone actually is, how does an ozone machine work, and how effective ozone air purifiers actually are.

Most importantly, we will address the No. 1 concern connected with all air purifiers that use ozone generators:

Is ozone generators safe, or are they bad for your health?

In the end, we’ll list 5 specific reasons why the use of ozone cleaners might be a really bad idea.

With that in mind, let’s first look at what ozone actually is and why it’s used to destroy indoor air contaminants:

What Is Ozone?

Ozone is a gas, composed of 3 atoms of oxygen. Chemically, we denote its formula as O3. The oxygen safe oxygen we breathe and continuously need to sustain life is composed of 2 atoms of oxygen and denoted as O2.

Here is a depiction of these two molecules:

ozone molekule with 3 oxygen atoms vs oxygen with 2 oxygen atoms
Ozone is a pale blue that has consisted of 3 atoms of oxygen. It’s highly reactive.

What are the differences between oxygen (O2) and ozone (O3)?

Ozone is much more reactive than oxygen. Due to electronegative imbalance in the O3 molecule, this chemical gas will readily react with pretty much anything.

That makes it deadly for airborne air contaminants, like mold, bacteria, and viruses. On the other hand, that is also the reason for the safety measures that were put in place.

How can we detect ozone with our own senses?

Despite being of pale blue colors, it’s usually present in low concentration and is thus invisible (much like air itself).

However, ozone can be smelled. It has a distinctively pungent smell similar to that of chlorine. If you’ve ever attended a public pool, you’ve smelled chlorine; that’s how ozone smells as well. It can be picked up by our noses even at very low 0.1 ppm concentrations.

Because it’s reactiveness is a useful feature when you need to destroy little species (like mold, dust mites, bacteria, and viruses), it’s used in air purification technology. It needs to be said that the use of ozone for air purification has both questionable effectiveness and presents healthy concerns.

Machines that do create and use ozone is such a way are called ozone generators or ozone machines (ozonator is also a valid term):

How Does An Ozone Generator Work?

In most basic terms, an Ozone generator uses electricity and normal O2 oxygen to create ozone or 03. In nature, ozone is created air by lightning (corona discharge) or by Sun (UV light).

Here’s the basic equation of how ozone is created:

O2 + Power (Electricity, UV) = O3

Ozone air purifiers work by emulating these two procedures. Electricity is used either to create lightning-like electric discharge or to power a UV-light:

how ozone is created within an ozone generator
Ozone is created via UV light or electric-discharge, used to disinfect the air, thereby returning it to the original oxygen state.

Ozonators work you either of these 2 basic principles:

  1. Corona discharge: O2 is split into 2 individual oxygen atoms via electrical discharge (spark, lightning-like effect). These newly created elemental oxygen atoms (O) will quickly bind together to form ozone (O3). According to Oxidation Tech, you need 0.372 kWh of electricity to create 1 lb of ozone.
  2. UV light: UV-C light filter basically simulate Sun’s radiation, and thereby create ozone or “activated oxygen”. According to the FDA, the ozone generated via UV light to be effective, it needs to surpass the levels considered to be safe for humans.

As you can see, EPA, CDC, as well as FDA, warn about the dangers of using ozone generators. Why then do we actually use the ozone machine?

Manufacturers do claim these ozonators are ‘safe’ and ‘effective’. We will cover safety concerns later on. Let’s focus on the effectiveness of ozone generators when they are used as air cleaners.

There is a lot of evidence they are harmful to the body. The only redeeming quality the ozone machines may have is superb and unmatched effectiveness. Let’s look at how effective they are:

Are Ozone Generators Any Good?

When ozone air cleaners are used as air purifiers, they don’t work like HEPA-based air purifiers companies like Coway, Blueair, Winix, Hathaspace, Honeywell, Levoit, and Alen produce, to name just a few. Even if you check the list of top-rated air purifiers, you’ll see that most of them don’t produce ozone at all.

What does ozone do in air purifiers?

Ozone generator producers usually come with a premise that these ozone machines take care of:

  • Mold.
  • Bacteria.
  • Viruses.
  • Dust, pollen, and smoke particles.
  • Volatile organic compounds or VOCs.
  • Odors, like cigarette smell or kitchen oil smell.

What is more, ozone generators don’t merely capture or adsorb air pollutants like other air purifiers. The destructive nature of ozone, as they say, ensures that all air pollutants are destroyed. That means bacteria, viruses, and mold are inactivated or even eliminated on a molecular level.

Make no mistake:

Ozone is highly capable of destroying any kind of organic material. However, for that, a high concentration of ozone is needed.

What really needs to be focused upon is how well do ozone generators do their job at very very low concentrations, considered to be safe for humans.

Let’s look at each of the air pollutants ozone generators are supposed to remove and see if there are any scientific studies that might back those claims:

Do Ozone Generators Kill Mold?

Mold is the primary air pollutant that ozone generators are expected to work against. HEPA filters only capture mold which can grow inside the air purifier. To know more about mold, you can read about the best air purifiers for mold with UV-C filters here.

A 2017 Italian evaluation study about antifungal activity and ozone has the following to say about the effectiveness of ozone to kill mold:

“Although the antimicrobial efficacy of ozone has been evidenced by several authors, various studies have already shown a lack of this activity against molds.” (2017 Italian study)

What is more, a 2019 international study of gaseous ozone on microbial killing capacity has concluded that “ozone alone may not an adequate means of controlling manure-based pathogens on complex surfaces”.

Following these studies, it seems that ozone doesn’t kill mold effectively, or at least not in the concentration safe for humans. That alone is already a big blow against the use of ozone machines.

Do Ozone Generators Kill Germs (Bacteria And Viruses)?

When it comes to germs, there is scientific evidence that ozone generators might be effective, albeit at higher concentrations of ozone.

An old 1983 study, published in the Journal of Clinical Pathology, has investigated the microbiological effects of domestic ozone generators against bacteria. This is what they have written in conclusion:

“A useful bactericidal action, against a variety of human pathogens was achieved with ozone concentrations between 0.3 to 0.9 ppm.” (1983 study)

However, they do add that these bactericidal ozone concentrations are quite high. That’s almost 40 years ago. Between then and now there is quite a lack of studies that would show that ozone generators are effective at killing germs.

Do Ozone Generators Remove Odors?

Odor removal is another interesting effect ozone generators might have. Ordinary mechanic filters like HEPA filters can only remove solid particles. Odors, on the other hand, are in gaseous form.

Standard air purifiers use activated carbon filters made out of granular charcoal to adsorb odor. Ozone machines could, in theory, destroy odor like cigarette smoke, cooking oil odor, and level volatile organic compounds (VOCs) such as formaldehyde. After all, the natural action of ozone is to quickly bind to any organic molecule and thereby destroy it.

This theory of ozone generators removing odors, however, has not been of particular interest to the scientific community. It’s difficult to find appropriate studies that would prove or disprove if ozone machines remove odors.

Does Activated Oxygen Clean Air?

Clean air is usually referred to as air without air pollutants. The most common and widespread air pollutant is dust (in both small and large particles) and other similar particulates.

HEPA filters, for example, are specialized to remove these particulates. HEPA literally stands for high-efficiency particulate air, after all.

It’s important to note that ozone generators are believed to have no direct effect on particulates. In short, ozone is not used to destroy dust particles. In such a way, we can say that activated oxygen by and of itself is not designed to clean air of dust and other particulates.

Does Ozone Kill Pollen And Other Allergens?

Pollen is one of the most common allergens that should, in theory, be destroyed by ozone generators.

However, pollen is not a living organism like mold, bacteria, or viruses, and would thus better be categorized as particulate.

In fact, AHAM actually considered it as a particulate. That’s why they have developed a specific technique to measure pollen CADR rating, used in room air purifiers.

Based on the available scientific research, it’s not possible to state if ozone kills pollen or not with any degree of certainty.

What Does The EPA Say About How Effective Ozone Machines

It makes sense to trust both scientific studies as well as government agencies when it comes to our safety, as well as the effectiveness of ozone generators.

EPA has put the effectiveness of ozone generators into question with this statement:

“Available scientific evidence shows that at concentrations that do not exceed public health standards, ozone has little potential to remove indoor air contaminants.” (EPA on Ozone Generators)

In short, it seems that ozone generators can’t be safe and effective at the same time. The primary concern should be put on safety. For effectiveness, we have other air purifiers as good or even better alternatives to ozone generators.

Finally, let’s address the safety concern of using ozone to remove indoor air pollutants:

Is Ozone Bad For You?

Ozone, created by ozone generators, has quite a destructive power. Even at low concentration, it may prove deadly to all sorts of air pollutants.

However, in almost every publication that talks about ozone generators as air purifiers, the focus is on the questionable safety of using such machines in our homes.

In the intro, the EPA states “When inhaled, ozone can damage the lungs”. The CDC and even the FDA seem to share this opinion. Here are direct quotes from these two government institutions:

“Exposure to ozone may cause headaches, coughing, dry throat, shortness of breath, a heavy feeling in chest, and fluid in the lungs.” (CDC on Ozone)

“Ozone is a toxic gas with no known useful medical application in specific, adjunctive, or preventive therapy. In order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals.” (FDA CFR Title 21)

When you have EPA, CDC, and FDA warning about the safety concerns about ozone, you might think twice when buying an ozone generator.

What is more, the FDA is apparently also doubtful about the effectiveness of ozone at concentrations that would be safe for humans.

To control ozone and ozone creation indoors, we have certain regulations in place. Here are just two of them:

  1. To be compliant with the FDA, all indoor medical devices are limited to 50 parts per billion of ozone produced.
  2. Indoor ozone levels should not exceed 100 parts per billion of air, according to the National Institute of Occupational Safety and Health.

All in all, almost every indication we now know seems to be a point in one direction:

Away from ozone and ozone generators.

Here is a short summary of the 4 reasons why the use of ozone generators is not recommended:

5 Arguments Against The Use Of Ozone Air Purifiers

  1. Safety concerns. Scientists have warned against the use of ozone for several decades now. FDA, CDC, and EPA are in agreement that ozone is a dangerous gas, not to be taken lightly. “If inhaled, ozone can damage the lungs,” according to the FDA.
  2. Ozone generators might not even be effective. Ozone is a highly reactive molecule, and ozone machines can create it in high enough quantities to be germicidal and to have an impact on indoor air quality. However, at low levels that are safe for humans, the effectiveness of ozone for a reduction in air pollutant concentrations are questionable at best.
  3. A lot is still unknown about particulates. Air purifiers should be good at removing small solid dust particles. Ozone generators seem not to remove or destroy them at all. This is just an example of the lack of data-based knowledge we have about ozone and ozone generators.
  4. How long does it take for ozone to dissipate? Answers range from up to 4-5 hours for higher concentration and as low as 20-30 minutes for low concentration. As of yet, there are no clear times of how long does ozone lasts available. Part of that is because there are numerous factors that influence the speed of ozone dissipation.
  5. You have alternatives. Ozone generators are actually a small niche of air purifiers. You have thousands of models of air purifiers that are well equipped to increase indoor air quality without the fear of ozone and its harmful effects.

All in all, using ozone is just not worth the risk. Not only are the health concerns very real; you also have concerns about the lack of air purification efficiency when ozone is used in low concentrations.

Nonetheless, it’s important to differentiate between domestic ozone generators marketed as air purifiers and commercial ozone machines:

A Word About Commercial Ozone Machines

Commercial ozone generators usually do not follow the same guideless as domestic ozone generators. Commercial units are used for mold mediation, general disinfection, and so on.

Machines like Enerzen commercial ozone generator 6,000mg are operated in open spaces or/and by professionals following specific protections, such as having a protective suit to limit the exposure as much as possible.

Commercial ozonators may produce a higher amount of ozone, and are, in general, not to be equated with residential ozone generators that are being marketed as air purifiers.

3 thoughts on “Ozone Generators: How Does An Ozone Machine Work? (+Safety Concerns)”

  1. I’m 60 ish and have had and used an ozone gerator near my kitchen for over 20 years. It was purchased from the gadget store, Sharper Image. I have used it, primarily after cooking to eliminate lingering food odors as I have a very low tolerance to smoke, oil and cooking related air borne smells. It’s usually only running for 30-60 minutes when I think it’s necessary. So, only sporadic use. It just gives a clean, fresh air smell to the kitchen and gathering areas. Your article states that it smells like Clorine bleach. I disagree. I didn’t even know it was supposed to be harmful until recently. I, nor my family have ever had any ill effects from using it. As the article says, perhaps because it’s in small doses. I don’t care about it not being very effective at eliminating bacteria and viruses. That would just be a bonus. But it certainly does take an uncomfortably strong cooking odor from your stuffy closed up winter home in a hurry and replace it with the fresh scent you get after of a spring thunder shower. And there are no dirty, expensive filters to deal with either. So, since it hasn’t done us in yet, I’ll have to make my own judgment as to how much “danger” it poses to our health. I’ll probably continue to use it for as long as it holds up. Thanks for your time and opinions.

  2. I, just this week purchased a commercial ozone generator from Amazon. It produces 10,000 mg/hr of Ozone. I purchased it to neutralize pet urine smells from homes. The areas to be treated will be vacated and sealed during treatment and will remain sealed for several hours after each treatment is completed. I will make as many periodic treatments as necessary to neutralize the urine odor. I realize the dangers of ozone and will not expose myself or anyone else to ozone. Thank you for this article. Neither the Amazon advertisements for ozone generators (made in China) nor the instructions included with ozone generators are emphatic enough about the dangers. I made the purchase because other purchasers swear by the ozone generators.


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