What Does Ozone Do

In your search to learn more about ozone, you’ll likely end up reading a lot about the benefits of ozone, especially for its indoor use. Since so many manufacturers are selling ozone generators as air cleaners, they will try to make ozone seem like something you want to have in your home to improve your health.

However, many of these resources aren’t reliable as they don’t draw facts from credible scientific sources. 

In this article, we will talk about what ozone is, what does ozone do, and what is an ozone machine.

We will try to demystify ozone as there are many controversies around it and give you the most accurate possible advice about these devices.

What Is Ozone?

The most literal answer to “what ozone is” is that it’s a molecule made of three oxygen atoms.

Two oxygen atoms inside are forming oxygen’s most basic molecule. That’s what we breathe to sustain our life on a daily level. The third atom here is free as it can detach and re-attach to other molecules. This means that this free-floating third ozone atom can change the chemical composition of other molecules.

This ability of ozone to react with and alter other substances’ chemical structure is the basis of many pro-ozone claims by ozone-generator manufacturers.

You may have heard about ozone before also in this other context: it’s one of the most critical layers surrounding the Earth’s atmosphere (positioned in the atmosphere’s upper layer) and protects from UV wavelengths. When scientists talk about air pollution, they often mention the destruction of the ozone layer, and the increasing levels of the Earth’s heat, due to the lack of protection from the sun’s radiation.

The ozone is being formed either in the upper atmosphere as we described or in the lower atmosphere, e.g. ground-level ozone.

When we speak about ozone, there are two ‘types’ that are important for us. We call them the ‘good ozone’ and the ‘bad ozone’ since the upper-atmosphere ozone serves as protection. At the same time, the ground-level one is considered a secondary pollutant (it isn’t emitted directly but formed as a byproduct of our polluters such as car exhaustion gases, factories, chemical plants, solar radiation, etc.). 

Let’s look a bit more into the topic of good and bad ozone.

The Good Ozone

Since above-atmospheric ozone is our most essential shield from UV radiation and skin cancer, we call this type of ozone ‘good ozone’. This kind of ozone is also critical to plant survival, and thus for the survival of all the herbivores (often food to carnivores, so it’s vital for everyone).

The upper ozone layer is being destroyed mainly by chemicals that contain CFC (chlorofluorocarbons). These chemicals are primarily found in, e.g. freon, commonly used for heating systems, refrigerators, air conditioners, etc.

While some efforts have been put into reducing the ozone layer destruction, the hole is still reappearing, especially in the Southern hemisphere of the Earth, for about three months of the year.

The Bad Ozone

Being exposed to ozone can have various consequences on human health, depending on previous risk/sensitivity factors. Children are the most vulnerable to bad ozone, as the lungs are still developing throughout childhood.

Other vulnerable groups are people whose immunity is weakened for any reason, those who lack vitamins C, R, or D, and those who suffer from any lung disease such as asthma, chronic bronchitis, etc.

When people are exposed to ground-level or ‘bad ozone’ for too long, the pollution can cause inflammation processes and airways damage. This usually results in coughing, irritation, increased lung sensitivity to infection, and more often, emergency room visits.

How Is Ozone Harmful?

High concentrations of ozone can react with organic matter outside of the human body. However, the same chemical properties that allow it to do so allow it to react with such organic matter within the body, leading to potentially harmful health outcomes.

Inhaled ozone can create lung damage, especially if inhaled in larger amounts.

However, even small amounts can lead to unpleasant symptoms such as coughing, chest pain, throat irritation, and short breath.

For those who already suffer from respiratory diseases, exposure to ozone may severely compromise the body’s ability to fight off respiratory infections. Furthermore, chronic respiratory conditions can worsen, and people suffering from them might experience additional trouble.

Even if you are completely healthy, it’s still possible to experience some breathing issues in interaction with ozone.

If the ozone levels are high, it’s highly recommended not to exercise, as you are breathing more ozone into your lungs, causing damage and increasing the risk of all of the above-mentioned harmful effects to your respiratory system.

Recovering from ozone’s harmful effects is possible if you’ve been exposed only shortly. However, the longer the exposure and the higher the levels of ozone you’ve been exposed to, the less certain it is that you’ll be able to recover from its effects.

Companies that produce ozone generators often provide misleading information on the effects of ozone on your health. For example, they often use terms such as ‘energized oxygen’ or ‘pure air’. These terms are coined to convince you that the ozone is some kind of healthier oxygen. However, this isn’t true. Its chemical properties are significantly different from oxygen, and their role is entirely different. You should not rely on ozone as some kind of health protection.

What Is an Ozone Generator?

An ozone generator is a machine that creates ozone and releases it into the air. These machines are often being sold as air purifiers for indoor spaces. The manufacturers market them as useful, effective, and safe in such cases. However, you should be aware that these claims are usually not valid. While some devices produce ozone as a byproduct, we mainly focus on those machines that intentionally produce ozone. However, we will also briefly explain machines that produce ozone as their secondary function. 

For example, electrostatic precipitators and ionizers produce ozone as a byproduct. Their internal mechanisms are organized so that besides their primary task, they also create ozone.

Ionizers used to be very popular, and many households opted to purchase this kind of machine to eliminate odors and clean their indoor air. However, they were banned in 2005 when their rather harmful effects were proven for the first time. Although ionizers produce less ozone than ozone generators, they are not recommended to be used as indoor air purifiers.

As described earlier in this article, the original ozone generators produced ozone by breaking oxygen apart. The molecules are being broken into atoms, which can later attach to other oxygen molecules. This is how larger amounts of ozone are being formed.

There are two ways to accomplish this:

  • Using electric discharge for ozone production. The split molecules of regular oxygen in the air are split into atoms that attach to other oxygen molecules to form O3 molecules. This is also called ‘silent corona discharge’.
  • A mechanism that uses processes similar to the sun’s ultraviolet radiation to split the oxygen molecules into atoms. This way is, in fact, less efficient than the previous one in producing ozone.

Is an Ozone Generator an Effective Way to Control Indoor Pollution?

Although many manufacturers claim that the ozone’s highly reactive nature makes it attach easily to pollutants, particularly odor compounds, but also viruses, mold, and bacteria, this has never been scientifically proven.

Several studies have tested these machines in hospital settings where it was essential to stop the spreading of mold and bacteria. However, the researchers concluded that dangerous ozone levels would be necessary to achieve that. Therefore, ozone generators are not recommended for mold and bacteria spreading prevention, as the price to be paid is too high.

But then, does it at least work against volatile organic compounds, also known as odors? Well, in case you’ve already purchased this machine, you may be hoping for a positive answer, and there is one, but with an unpleasant condition: yes, they work against odors, but it takes sound ten lifetimes, as it was approximated that for the 14 most common compounds it would take more than 880 years to be broken down. Only styrene takes as ‘little’ as 4 hours, and formaldehyde would require fascinating 4,400 years to break down. So, unless you want your ozone generator to travel through generations to prove this point, we recommend not wasting your time and money on this machine.

Finally, ozone generators are not efficient against particulate matter such as pollen, dust, or any other allergens and pollutants from the air.

Can the Following of the Directions of Ozone Generators Manufacturers Harm Me?

Unfortunately, achieving unrecommended high levels of ozone is very much possible even if you follow the manufacturer’s operating instructions.

The market has to offer so many different brands and types of ozone generators. These can vary in the amount of ozone produced, so in many cases, especially if ozone production is low, the amount may not exceed recommended levels.

However, certain studies have shown that placing an ozone generator intended for rooms of up to 3000 square feet produces dangerous ozone levels in a very short time. In an in-home environment, opened or closed doors can play a massive role in the speed at which these ozone generators produce dangerously high levels of ozone that significantly exceed public health standards. For example, if units are operated at low settings and the doors are kept open, the ozone levels do not exceed recommended standards.

Controlling the amount of ozone exposure with an ozone generator can be pretty tricky, as it depends on many factors:

  • Device power: more powerful devices, in general, generate higher levels of ozone;
  • Space size: the smaller the space, the faster it fills up with ozone;
  • Ventilation: open doors and windows slow down the production of ozone;
  • The proximity of a person to the generator: the closer you are to the generator, the more you are exposed to the ozone.

What Can Be Done?

Some vendors recommend paying attention to space sizes. However, this is often not sufficiently defined for you to rely on it entirely. Furthermore, some generators also have a setting that allows you to adjust the levels of ozone outputs. However, this output is usually disproportional to what is stated by the control setting. These scales are not very precisely adjusted, so ‘low’ and ‘high’ may have many different levels in between, out of which many may be toxic.

Another piece of advice is to lower the ozone setting once you start to feel its smell in the air. While this may seem like a good measurement, there are considerable individual differences in people’s actual sensitivity to it. For example, one person might detect ozone at lower levels. At the same time, another can take a long time before they start feeling it in the air. Another issue here is that we quickly adapt to it, so our ability to sense the ozone nasally will deteriorate the longer we are exposed to it. The smell of ozone can indicate that there is too much ozone in the air, but the lack of smell is not a good indicator that the air is safe to breathe.


Suppose you are worried about indoor pollution levels in your home. In that case, there are much more efficient and reliable ways of dealing with it, compared to ozone generators, ionizers, etc. Ozone that comes in either its pure form or when combined with other chemical compounds can severely harm your health, especially the respiratory system.

Inhaled ozone can damage your lungs. Even the amounts considered low can be harmful to your health, especially during repeated or prolonged exposure. Sensitive individuals (those suffering from chronic respiratory issues) are at a greater risk of worsening the symptoms of their illnesses. Still, also they risk compromising the body’s natural ability to fight against respiratory system bacteria, viruses, and common infections. 

So far, almost no research has backed up the idea that ozone generators can be beneficial in fighting against indoor pollution, volatile organic compounds (smells), or particulates. Instead, studies reveal that it’s easy for the concentrations of ozone produced by ozone generators to exceed the recommended health standards, regardless of whether the user is following the vendor’s/manufacturer’s instructions on how to use the machine.

The concentration of ozone in the air is usually affected by multiple factors: space size, ventilation, the person’s proximity to the machine, etc. This makes it very difficult for the user to keep the ozone concentration under control at all times.

The existing recommendations on dealing with ozone level control appear to be insufficient and unreliable, as there are no sensitive enough built-in measurers or control systems to rely on. Our internal ability to ‘sense’ or smell the presence of ozone in the air we breathe is suspect to individual differences.

Finally, the concentrations of ozone that are not harmful to health are entirely useless in fighting indoor pollution. Levels that might break up specific other harmful/unpleasant molecules are detrimental to our health, so using ozone for air pollution is not efficient, as the ozone itself produces other chemicals that can cause irritation or corrosion.

If you want to control indoor air pollution, you should look to eliminate pollution sources, increase air ventilation, or use a HEPA air purifier