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.
