More than 80 million Americans use an air purifier to improve air quality and essentially protect their health. However, it’s crucial to know if air purification also creates toxic byproducts such as ozone.
Ozone generators and air purifiers with ionizers or UV bulbs that emit wavelengths of 185nm produce ozone. However, air purifiers with HEPA, activated carbon, TiO2, or pre-filters do not emit ozone. Air purifiers with UV-bulbs that emit light at 256 nm also don’t produce ozone and are safe to use.
This article is a detailed guide on ozone, its role in removing airborne contaminants, its potential production from air purifiers, and its harmful effects. The post also recommends some non-ozone producing high-quality air purifiers that you can consider investing in.
What is Ozone?
Ozone is a highly reactive and unstable compound made up of three oxygen molecules. While, normal oxygen gas contains just two oxygen atoms, and makes up 21% of the surrounding air.
The third oxygen atom (nascent oxygen) in ozone makes it unstable. To achieve stability (form an oxygen molecule), ozone readily decomposes and releases its third atom, which is donated to surrounding substances.
Side Effects
Ozone naturally occurs in the atmosphere and surrounds the Earth in the form of a sheath that protects us from direct exposure to harmful sun rays.
However, when ozone is produced artificially, it can react with the biological molecules of the body, resulting in severe complications, such as:
- General Symptoms: Nausea, vomiting, headache, fever, skin and eye irritation.
- Respiratory Distress: Upon inhalation, ozone irritates the lung and damages lung tissue causing dyspnea (difficulty in breathing). This damage makes the lung more sensitive to environmental toxins, and can cause severe wheezing, coughing and sneezing. It may also exacerbate disorders like asthma and emphysema.
- Aggravation of Immune System: Ozone triggers the immune system and sets the body into auto-immune mode, destroying the immune cells. Initially, the aggravation leads to allergic reactions, but once immune cells start dying, the body becomes susceptible to various infections.
- Neurological Damage: The respiratory distress caused by ozone reduces the oxygen supply to the brain, which manifests as confusion and hallucinations. If the oxygen levels in the brain are not restored promptly, the ozone damage may lead to permanent loss of memory and other essential cognitive functions.
- Cardiovascular Disorders: The continued lack of oxygen may lead to myocardial infarction, atherosclerosis of the coronary artery, and pulmonary heart disease.
Risk Factors
People most susceptible to ozone damage are:
- Pregnant Women: Ozone exposure is linked to miscarriage, especially early in the pregnancy.
- Children: Lungs in children are weaker and still developing and are more susceptible to ozone toxicity.
- Elderly: With age, the immune system weakens, and an older person may develop many disorders. This renders the elderly a significant risk population for ozone damage.
- Immunocompromised Individuals: The immune system is crucial for protection against ozone damage. This means patients with immune disorders are at high risk of significant damage upon ozone exposure.
Safe and Dangerous Levels of Ozone
As per the Environmental Protection Agency (EPA), ozone exposure of 0.1 parts per million (ppm) for 8 hours is considered safe. However, beyond that level, ozone can start affecting our health, manifesting as progressive, debilitating symptoms, depending on the concentration and length of exposure.
However, given the toxicity of the gas, this safe exposure is allowed only for specific purposes, such as disinfection, medicinal therapies, and air and water purification.
Note that ozone is a potentially lethal gas; an hour-long exposure to 50 ppm or more ozone can cause death.
Do Air Purifiers Produce Ozone?
Air purifiers are appliances that remove toxic substances from the air and make it safe to breathe. However, there are now a large range of air purification systems and each uses a specific filtration mechanism, or a combination of several methods.
Air Purification System
Whether or not an air purifier creates ozone depends on its filters and mechanism of air purification.
Pre-Filter
Almost all air purifiers have a pre-filter that has large pores (100 microns to 3000 microns). It traps large airborne contaminants like dust and debris. However, other smaller particles like pet hair, dander, pollen, and microbes pass through it.
It does not play a significant role in air purification but protects other filters and the air purifier in general from dirt buildup and damage from debris.
Pre-filters do not cause an air purifier to create ozone.
True HEPA Filter
A HEPA filter is one of the most effective filters available. It has microscopic pores that can capture particles as small as 0.3 microns with over 99.97% efficiency. This enables the removal of most pollutants and germs like bacteria and mold spores.
True HEPA or HEPA-like filters do not result in an air purifier producing ozone.
Activated Charcoal Filter
An activated charcoal filter is found in most modern air purifiers. When heated and oxygenated, charcoal becomes porous. Gases and volatile organic compounds (VOCs) in the air react to this porous carbon, become adsorbed on the surface, and are trapped in the pores.
This filter removes odor molecules and poisonous gases, such as formaldehyde, from the air, making your room smell fresh.
Activated carbon filters do not cause an air purifier to create ozone.
TiO2 Filter
A ‘TiO2 filter’ coated with photocatalytic titanium dioxide. Like carbon filters, TiO2 removes VOCs. It breaks the gas through oxidation, which kills any smells. It is also considered an active antimicrobial and kills pathogens.
An air purifier that uses a TiO2 filter does not create ozone.
Ionizer
Ionizers emit negative charges in the air purifier. These charges create static electricity that acts on particulate matter, causing them to fall on and stick to the ionizer and surrounding surfaces (couches, chairs, tables, the floor etc).
Although negative ions are naturally present in the air and are safe, their artificial production through ionization leads to ozone formation. Ionizers produces high-energy particles that undergo molecular reactions, which creates ozone as a byproduct.
Note that not all ionizers generate a large number of negative ions and hence, do not necessarily produce large amounts of ozone.
UV Light Bulb
Some air purifiers have UV light bulbs that emit ultraviolet wavelength (UV-C 256 nm). This is germicidal and kills most pathogens that flow with air inside the air purifier.
However, while most UV light bulbs emit UV-C light, which is safe and effective, some bulbs are programmed to produce ultraviolet rays of a different wavelength. Emission of 185 nm causes oxygen molecules to split and create ozone.
Air purifiers with UV light bulbs that emit light at 185 nm will indicate the production of ozone on their packaging and in the user manual. Air purifiers that emit UV-C light in the order of ~256 nm will not produce ozone.
Ozone Generator
Ozone generators are not filters but devices that rely on ozone for air purification. The gas readily decomposes when exposed to surrounding air and gives up its third oxygen atom. The oxygen atom reacts with airborne chemicals and gases, changes their chemical composition, and thus, gets rid of their toxic forms.
Ozone is used for air (and water purification) because it changes the chemical makeup of toxic gases and VOCs. Commercial ozone generators produce up to 5,000 mg of ozone per hour to sanitize the environment.
This production is achieved by splitting surrounding oxygen molecules via electric shock. The single atoms created in the process then attach themselves to the available oxygen molecules forming ozone.
Although ozone mainly acts on gases, research has found that it also inhibits bacterial growth by about 30%.
These units are not operated 24/7 like other air purifiers. Instead, they are occasionally used for shock treatment to remove odors, and should never be used when people are present.
Best Ozone-Free Air Purifiers
Thankfully, there are plenty of air purifiers that are ozone free. These air purifiers typically use a combination of True HEPA, activated carbon and pre-filters. Many of them also use UV-light, but within a wavelength range that does not produce ozone.
Here are three of the best air purifiers that don’t produce ozone:
PureZone 3-in-1 True HEPA Air Purifier
PureEnrichment has been the face of premium American domestic appliances, and PureZone is their most popular series. PureZone 3-in-1 True HEPA Air Purifier features a three-stage filtration system that guarantees the removal of 99.97% of airborne contaminants and does not produce ozone.
The three filters installed in the series are a True HEPA filter, an activated charcoal filter, and a UV-C light bulb. While the HEPA filter and the UV-C bulb remove particulate matter and bacteria, the carbon filter extracts gases and VOCs from the air, thus, ensuring fresh and clean air.
Other than high-quality filtration, this unit also comes with versatile, easily-navigable controls. The user can adjust fan speed, timer, and various other things with a simple screen touch.
Apart from this, PureZone appliances are designed to conserve energy and reduce your electricity bills. By investing in PureZone 3-in-1 True HEPA Air Purifier, you are assured of saving bucks in the long run.
It also comes with a 5-year warranty plan, and considering the improved filter life and reputed customer service of the company, your air purifier will last a long time if maintained adequately.
Alen BreatheSmart Air Purifier 75i
This Alen BreatheSmart Air Purifier is made for large rooms, basements, and offices. It provides extensive coverage of over 1300 sq. ft. Using its medical grade 13 HEPA filter, it cleans every 30 minutes to effectively remove microbes, dust, pollens, pet dander and hair from the environment without producing ozone.
It also comes with adjustable controls that allow you to have a personalized, comfortable experience. Moreover, it has an LED bulb that lights up various colors to notify you of the room’s air quality and filter life.
Afloia Miro Pro 2-in-1 Air Purifier and Humidifier
Afloia Miro Pro 2-in-1 Air Purifier and Humidifier is a combination unit, perfect for dry areas. Its air purifier is the central unit that can operate without a humidifier. The clean air from the air purifier is sent to the humidifier to add moisture and is then dispersed into the room.
The air purifier is a three-tier filtration system consisting of a pre-filter, a True HEPA filter, and an activated charcoal filter. On the other hand, the base unit is an evaporative humidifier, equipped with premium features, enabling it to achieve and maintain the set relative humidity within minutes.
For people living in hot and humid climates, Afloia also offers a combination unit having an air purifier and a dehumidifier. It is also highly efficient and worth buying.
Is Ozone From An Air Purifier Harmful?
Most ionizing air purifiers produce up to 50 parts per billion (ppb) of ozone, whereas the safe level of ozone exposure as per EPA is 0.10 ppm (100 ppb) over 8 hours. Considering this, repeated and long-term exposure to ozone gas from air purifiers can be harmful to health.
Although manufacturers of ozone generators, and air purifiers that produce a fraction of ozone as a byproduct claim it to be safe, one should never forget that the gas is hazardous, and even minimal exposure can land you in severe and irreversible health issues.
Therefore, it is always better to buy appliances that do not create and emit any amount of ozone gas.
Can You Smell Ozone?
Ozone has a distinct, chlorine-like smell, which is detectable when the gas is greater than 0.1 ppm in the air.
When inhaled, ozone can damage the lungs. Ozone concentrations above 0.10 ppm are considered dangerous, you should immediately vacate the house and promptly consult a physician if you think you have been exposed to ozone.
How Can You Tell If You Are Being Affected By Ozone?
Irritation in the eyes, nose, and throat, shortness of breath, headache and nausea are the initial symptoms of exposure to elevated levels of ozone. If you start showing these medical signs, ozone toxicity may be the cause and you should seek medical attention.
Are There Any Air Purifiers That Do Not Produce Ozone?
Air purifiers that do not contain ozone generators, UV bulbs, or ionizers do not emit ozone. Product descriptions and user manuals can be checked before buying a product as the production of ozone should be provided.
