Do Humidifiers Produce Ozone? – All You Need To Know

Humidifiers are appliances that improve and regulate the moisture content in the air and are essential in dry areas. But do they produce any toxic byproducts like ozone? 

Standard humidifiers do not produce ozone. However, negative ion humidifiers, or ‘humidifier ionizers do produce a small amount of ozone. Certain humidifier-air purifier combination units can also create ozone. Combo units with ionizers, UV bulbs, and ozone generators may create and emit ozone.  

This article explains what ozone is and how it is created. We then take you through the various humidifiers and elaborate on how they may or may not produce ozone.  

What is Ozone? 

Ozone is a molecule made up of three oxygen atoms that forms a protective sheath around the Earth in the upper atmosphere.  

Oxygen makes up around 21% of the surrounding air and exists as a molecule made up of two atoms. The third atom in ozone makes the compound highly unstable. Ozone readily donates the third (nascent) oxygen atom to other chemicals and volatile organic compounds (VOCs) in the air, so that it can form a stable oxygen molecule.  

Apart from naturally occurring ozone, the gas is artificially produced by splitting water (H2O) via high voltage or UV light. This mechanism decomposes the molecules, forming oxygen radicals that bind to available oxygen molecules to form ozone. 

This manufactured ozone is used for air and water purification, paper production (pulp bleaching), and medicinal therapies.  

Side Effects 

Ozone is a dangerous gas, and according to the Environmental Protection Agency (EPA), exposure to more than just 0.07 ppm of ozone for 8 hours can manifest as progressive, debilitating symptoms, such as:  

  • Headache 
  • Nausea and vomiting 
  • Skin, throat, and eye irritation 
  • Coughing, sneezing, and wheezing 
  • Worsening of respiratory disorders like asthma and emphysema 
  • Shortness of breath 
  • weakening of the immune system 
  • Permanent neurological damage 
  • Myocardial infarction, pulmonary artery disease, and coronary atherosclerosis 

While headache, nausea, and allergies are initial symptoms, the signs can worsen depending on the level and length of exposure.  

An ozone exposure of 50 ppm for an hour can also prove fatal.   

Risk Factors 

Groups that are at significant risk of ozone damage are: 

  • Pregnant women 
  • Children and elderly 
  • Immunocompromised individuals 
  • Outdoor workers 

Humidifiers and Ozone Production 

Standard humidifiers without integrated ionizers, air filters, and other purification-related mechanisms do not produce ozone. 

A standard humidifier generally works by using a rotating fan to draw dry air in, which is then circulated through the humidifier. A humidifier has a water reservoir (called a bucket) that stores a specific capacity of water, which the unit converts into mist or vapors. This mist is then added to the air and the humid air is dispersed into the room.

Water can be converted into mist or vapors by two different mechanisms, which determines how a humidifier is classified: 

  • Evaporative Humidifier: These have a heating element that boils water and leads to vaporization. 
  • Ultrasonic Humidifier: These have a metallic membrane that vibrates at an ultrasonic frequency, propelling tiny water molecules (mist) into the air. 

Since the process doesn’t involve the splitting of oxygen molecules, standard humidifiers do not produce ozone. 

However, ‘humidifier ionizers’ produce negative ions and in doing so, create a small amount of ozone. This type of humidifier is not common, and the production of ozone is clearly advertized on the packaging.  

Humidifier and Air Purifier Combination Devices 

Some humidifiers come in combination devices with air purifiers. While the humidifier component doesn’t produce ozone, other components in the combo unit may create the gas. 

A humidifier-air purifier combo device that has any of these three components can produce ozone: 

1. Ionizers  

An ionizer is a device that emits negative ions. This creates static electricity that causes particles in the air to fall down and settle on the ionizer and other surfaces inside the unit.  

Negative ions are high-energy particles. While acting on the particles in the air, they also undergo molecular reactions that produce ozone as a byproduct.  

Note that some ionizers generate regulated amounts of negative ions that do not necessarily generate ozone.  

2. UV Bulbs 

Humidifier-air purifier combo units with UV light bulbs usually emit UV-C light (256 nm). This wavelength is germicidal and kills airborne microbes, including bacteria.  

While most UV bulbs produce UV-C, some of them emit different wavelengths. Ultraviolet light in wavelengths of 185 nm can split oxygen molecules and create ozone.  

3. Ozone Generators 

Some humidifier-air purifiers have ozone generators that can artificially generate about 5000 mg/hr of ozone. Ozone then neutralizes the toxicity of gases in the surrounding air by changing their chemical composition. They are also capable of restricting bacterial growth by 30%.  

Ozone generators are not used 24/7 like regular air purifiers or humidifiers. They are primarily used commercially for odor removal through shock treatment.

It is believed that ozone generators produce higher ozone concentrations than the safe limit of 0.1 ppm. Therefore, they are not recommended and in the state of California their use has even been banned.

Other than these components, humidifier combo devices that use a pre-filter, True HEPA filter, activated charcoal filter, UV-C (256 nm) or TiO2 filter do not create ozone, and are safe to use.  


Does a Humidifier Add Oxygen To the Room? 

Humidifiers do not affect oxygen levels in a room. Humidifiers only influence the amount of moisture in the air (humidity).

This confusion often arises from the concept of oxygen humidifiers. However, oxygen humidifiers are medical equipment that filters and humidifies supplied oxygen to prevent possible lesion of respiratory mucosa. Like all typical humidifiers, they, too, don’t increase oxygen in the room.   

Does a Humidifier Create Negative Ions? 

Some stand-alone humidifiers have an integrated ionizer that produces negative ions to remove particulate contaminants from the air.  However, most standard humidifiers do not have an ionizer component and do not create negative ions.

What is the Difference Between a Humidifier and an Ionizer? 

A humidifier is an appliance that improves humidity levels, while an ionizer is a device used for air purification to remove contaminants from the air. While ionizers are mostly found in air purifiers, they are also integrated in some stand-alone humidifiers for sanitizing the air.  

Do Humidifiers Purify the Air? 

Some humidifiers have antimicrobial filters or sanitization mechanisms that remove germs from the air. More effective air purification can be achieved with a humidifier-air purifier combination unit.

Here are the best humidifier-air purifier units you can consider buying: 

Afloia 2-in-1 MIRO PRO Air Purifier and Humidifier 

The Miro Pro 2-in-1 Air Purifier and Humidifier is one of the most popular appliances by Afloia. It comes with a central three-tier air purifier and an evaporative humidifier. 

The humidifier provides mist-free humidification and is ideal for people with coughs and allergies. It comes with an auto-shut-off feature that turns the unit off once the water bucket is empty, thus aiding in energy conservation.  

The air purifier features three-stage filtration comprising a pre-filter, a True HEPA filter, and an activated charcoal filter. This combination removes more than 99% of all airborne contaminants five times an hour, ensuring fresh-smelling, clean air at all times.  

It comes with multiple adjustable controls like fan speed, timer, and LED controls, which enable the user to have a comfortable and personalized experience.  

The device provides extensive coverage of 219 sq. ft. and is ideal for small to medium-sized spaces.  

Dyson Pure Humidify + Cool 

Dyson is a renowned brand dealing in domestic appliances, and their Pure Humidify and cool unit is our next recommendation. Apart from working as a premium humidifier and air purifier, this model can be a makeshift fan in the summertime.  

The humidifier has a one-gallon tank suitable for mid-sized and large rooms. On the other hand, the air purifier section constitutes a 360-degree HEPA filter, pre-filter, and an activated charcoal filter. This ensures the removal of all airborne contaminants.  

As with all Dyson products, when buying this air purifier and humidifier combo, you can stay assured of the quality. If kept well, the unit can easily last 5 to 10 years. Even though it is a tad more expensive than other options currently available in the market, it is built with high-quality, dependable materials that save bucks on energy as well as maintenance.  

BONECO H300 Hybrid Humidifier and Air Purifier  

Next up we have BONECO H300 Hybrid Humidifier and Air Purifier. This is a 3-in-1 hybrid, which means that it can operate as a humidifier, as an air purifier, and as a combination of both. The hybrid version is highly efficient and provides optimal humidity and air purification, which is why it has become a people’s-favorite in no time.  

Its air purifier has a filter specially designed for allergens. Other than this, there also is a higher-spec comfort filter that removes dust, debris and other particulate matter. Although, it does not come with HEPA filter or an activated carbon filter, the device can improve your indoor AQI to a decent level. The unit also has a permanent pre-filter that removes dust, dander, and smoke.  

The humidifier has a direct-fill water base for convenient handling during refill and draining. Once the tank runs out of water, the auto-shut-off feature enables the device to turn off to save energy. What’s more is that it is easy to maintain and does not require rigorous scrubbing.  

This combo device also comes with a diffuser. You can add a few drops of your favorite essential oils into the diffuser, and enjoy a relaxing, clean and comfortable environment all day long. 

The device is compatible with the BONECO app, through which you can get real-time updates of the humidity and AQI on your smart device. All-in-all, this is a smart combo device that you consider buying.  

Russell Singleton

Russell holds a Bachelor of Science (Environmental and Marine Geoscience) with Class I Honors. He is currently completing his doctorate in science and is passionate about all earth processes, especially isotope geochemistry and paleohydrology.

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