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Which Air Purifying Systems are Ozone Free? – Comparing HEPA, Ionizers and UV-C

Which Air Purifying Systems are Ozone Free? – Comparing HEPA, Ionizers and UV-C

Ozone is one of the chemically reactive natural gasses found in the stratosphere. Ozone plays an important role in the cycle of atmospheric activity, filtering the sun's radiation to limit our exposure to UV rays on the surface of the earth.

While ozone is vital for a healthy atmosphere, it's unhealthy at ground level. Breathing in ozone causes respiratory distress in humans, and high exposure levels of ozone lead to asthma and allergy attacks in sensitive individuals.

The WHO and EPA both classify ozone as a pollutant at ground level. Ground-level ozone interacts with sunlight to form smog, and that's a problem for cities like Los Angeles and Beijing, which already have significant other contributors to low air quality.

Therefore, improving the air quality in your home with an air purification system should not include the use of ozone. Unfortunately, several air purification devices emit ozone during the process of "ionizing" the air.

This post unpacks everything you need to know about ozone-free air purification systems for your home.

Why Does an Air Purifier Create Ozone?

According to research, short-term exposure to ground-level ozone can cause several adverse health effects in people. Overexposure to ground-level ozone also results in higher mortality rates in cities where ozone levels are high, and air quality is poor.

Regular exposure to ozone can result in issues with the upper respiratory tract and the lungs. Individuals who experience years of prolonged ozone exposure may end up with reduced lung capacity.

So, why do manufacturers produce air purification systems with ozone?

Some air purifiers release ozone intentionally, while others produce it as a byproduct of the ionizing function on the device. Some manufacturers even claim that ozone can help with cleaning the air in rooms.

When we look at the science, we see that ozone is only three oxygen atoms bound together to form a molecule, O3. O3 is highly reactive, readily binding to other compounds in the air and the lungs, creating new molecular structures.

Those manufacturers state that this reactive nature of the molecule allows it to capture other particulate matter in the air. As a result, it converts them into less harmful molecules. Therefore, there would be some benefit to reducing the damaging effect of breathing in volatile organic chemicals  (VOCs) present in rooms in the home.

However, the reality is that the EPA has several studies on the efficacy of ozone produced by air purification systems is actually cleaning the air. There is some evidence to suggest that ozone effectively breaks down other harmful particles and chemicals in the air, such as those found in tobacco smoke.

However, it's important to note that ozone won't remove particulate matter like dust, pollen, and pet dander from the air inside your home. According to the research, ozone may even convert to other more harmful particles.

Some professional cleaning services utilize ozone to purify the air in rooms. The ozone supposedly helps kill the bacteria in the air and the room and remove any odors. However, these contractors use incredibly high ozone levels, and they remove it from the room and remediate the air before allowing reoccupation.

Which Air Purifiers Should I Avoid?

When purchasing an air purification system for your home, it's important to avoid models that could potentially add ozone to the room and ruin the air quality. Here is a quick list of the air purifiers to avoid in your research.

Ozonator Systems

Many companies market Ozonator products as a natural way to remediate and clean the air in your home. Also known as "ozone generators," these devices directly generate ozone and release it into the air in the room.

These machines create high concentrations of ozone in the air in an attempt to sterilize the room and kill any sources of bacteria and mold. Typically, these machines are unsuitable for use in occupied spaces and are part of an air remediation process utilized by professional air purification companies.

Ionizer Air Purifiers

There are plenty of portable air-conditioning units and some cassette models offering ionizing functions. It's a new trend in air cleaning, but it doesn't produce the results you expect. As part of the production of ions, the machine also creates and releases ozone into the air.

The idea behind the ionizer is that ions stick to the particulate matter in the air. They settle on the walls and floor of the home, where you clean them up in your normal housekeeping duties. It's a good idea, but the reality is that the ozone produced by these machines counters the benefits of the ions.

UV-C Lights

There is a new trend in air purification where manufactures are adding UV-C light traps to air purifiers. Supposedly, the concept behind the light trap is to help sterilize any contaminants and biological particles that make it through the air filter inside the air purification unit.

Some research shows that exposure to UV-C light kills pathogens like bacteria, viruses, and fungi. However, the study also shows that exposure to UV-C light in some particulate matter may also lead to ozone generation.

The light can break up the atoms in the molecules, causing them to change into other pollutants, such as ozone. Therefore, homeowners should avoid home air purification systems that utilize UV-C light traps as part of the system.

While the research shows that UV-C is effective in killing pathogens., the study uses intense light to what you find in a residential air purifier. It also involves exposing the pathogens to the light for durations of up to an hour, not a brief passage through an air purifier.

Electrostatic Precipitation

These air purification systems generate an electrical charge, imparting it on the particulate matter like dust and pollen in the air. The air purifier houses two plates, with each plate receiving an opposite charge to the other.

When the air passes through the plates, the charged particles become heavy, dropping out of the air column to the floor, sort of like the same effect as the ionizer purification system. While it's an effective system, the process of charging the air particles also causes the production of ozone.

PCO Systems

The Photocatalytic oxidation (PCO) process of air purification removes all gaseous pollutants from the air in your home. While manufacturers claim it's the most effective method of purifying the air, there is no peer-reviewed science on the effects and efficacy of these machines at cleaning the air.

The surface of the filter in these air purification systems receives coating with a chemical that reacts to the introduction of UV-C light. The chemical acts as a catalyst, breaking down pollutants into water. The photochemical reaction in the purifier creates "hydroxyl radicals," molecules that oxidize contaminants contacting the surface of the filter.

However, there is limited research on the compounds found in the breakdown of contaminants during the purification process. Therefore, some researchers state there need to be further studies into the byproduct chemicals created in the process.

Harmful products like formaldehyde, nitrogen dioxide (NO2), and ozone are all concerns for people using these air purification systems in the home.

Which Are the Best Ozone-Free Air Purifiers?

If you choose an air purification system for your home, we recommend going with a model with the following filters to reduce ozone and particulate matter in the air.

HEPA Filters

HEPA filters are the gold standard of filter air purification. These filters remove up to 99.97% of all particulate matter from the air. They are not effective at cleaning ozone and VOCs from the air, but they are an essential part of the air purification process.

Hybrid Carbon HEPA Systems

A hybrid filter system involves attaching an activated carbon filter to the HEPA filter in a two-stage design. The Carbon filter can trap ozone, odors, and VOCs in the air, before sending the air to the HEPA filter for final cleaning.


Photo Electrochemical Oxidation technology is a similar concept to PCO air cleaning. However, this system is an updated version, offering better performance and no harmful ozone or byproduct production.

The Photo Electrochemical Oxidation process is more efficient than PCO, creating the optimal concentration of hydroxyl radicals for destroying airborne pollutants. The system also doesn't make any harmful byproducts as part of the purification process.

The PECO system also involves the use of a light trap. However, this system uses the less harmful UV-A light spectrum. UV-A light doesn't react with oxygen molecules to form ozone, so it's a better choice than the traditional UV-C light found in many light traps.

How Can I Check the Air Quality in My Home?

If you think the air quality in your home may contain ozone, mold, pollutants, dust, or any other contaminants, call MI&T. MI&T is a professional air quality inspection service. We specialize in detecting the presence of mold spores in your home.

However, we offer you a full report on the air quality inside the rooms of your house. We can tell you if you have elevated levels of ozone, VOCs, or any other pollutants or particulate matter.

Call the professionals for a reliable, unbiased, and affordable inspection of the air quality in your home.