Air purifiers that use only high-efficiency particulate air filters (HEPA filters) do not emit ozone to clean the air. Ionizing air purifiers, due to their electrical charge, do create ozone. Consumer Reports has warned that they can emit potentially harmful levels of ozone. Some devices advertised as air purifiers purposely emit large amounts of ozone, the main component of smog.
CARB recommends that ozone generators not be used, except for approved industrial purposes where harmful exposure to ozone is avoided. Not only are ozone generators ineffective in cleaning indoor air, but inhaling ozone poses serious health risks to humans and animals. This fact sheet analyzes these health risks and provides effective alternative solutions to address indoor air quality problems. This fact sheet provides information on air purifiers, including the different technologies used, selection and use.
The use of air purifiers can be an important strategy to help improve indoor air quality (IAQ). For additional information on the IAQ, see the environmental health and safety guide on the IAQ. Ozone is a colorless gas found naturally in the Earth's upper atmosphere and protects us from harmful ultraviolet rays of the sun, although it can also form at ground level. It is known to cause the formation of free radicals in biological systems, which damage the tissues.
One mechanism of damage is the result of reactions between ozone and olefin and another of the reaction of ozone with electron donors (such as glutathione). Inhaling relatively small amounts of ozone can cause coughing, chest pain, throat irritation, and shortness of breath. Ozone-generating air filters are devices that create ozone on purpose to clean the air through chemical interactions that alter the compounds of the contaminants. However, this is also the mechanism by which ozone exerts harmful effects on health.
In addition, ozone is generally not effective in controlling indoor air pollution at concentrations lower. In other words, if the ozone concentration in the room is high enough to effectively clean the air, it is also high enough to create an inhalation risk for people in the room. In addition, ozone can even react with chemicals in the air and create harmful by-products (for example, for these reasons, EH&S does not recommend the use of electronic air purifiers or ozone generators under any circumstances). Electronic air purifiers (including ionizers, electrostatic precipitators, hydroxyl generators, and ultraviolet light) use electrical voltage to convert oxygen molecules or other species into their charged ionic components that inactivate air contaminants, in a process called bipolar ionization (BPI).The ionic components of oxygen are reactive radicals that are capable of removing hydrogen from other molecules.
In the case of bipolar ionization, positive and negative ions surround the air particles, destroying the germs and pathogens present, and the added mass helps the air particles to fall to the ground and pass through the building's air filter. However, BPI can emit ozone and other free radical species as a by-product, and may be less effective than other cleaning technologies, as charged particles from the air sometimes adhere to room surfaces (e.g., floors and walls) instead of leaking out. Filtering air purifiers pass air through a filter, where polluting particles or gases are trapped, and return clean air to a room. There is some popular controversy surrounding the extent to which air filters can reduce the presence of larger particles (such as pollen, household dust allergens, mold spores, and animal dander), but most of these large particles settle on household or office surfaces and cannot be removed with an air filter unless they are altered and resuspended in the air. Therefore, regular cleaning is the best way to eliminate larger allergens.
Air purification units have air volume limits that are identified by a “clean air supply rate” (CADR).A CADR is the cubic feet per minute (CFM) of air from which all particles of a given size distribution have been removed. The CADR indicates the volume of filtered air supplied by an air purifier per unit of time, with three different scores for smoke, pollen and dust, representing different particle sizes. The higher the CADR number for each pollutant, the faster the unit will filter the air for contaminants in a given size range. A carbon filter is the most suitable unit for removing gaseous VOCs from the air, for example, when new furniture are emitting gases.
However, if you notice an odor in a room, contact EH&S first for an evaluation. The best course of action is to eliminate and control the source of the odor, and EH&S can perform an evaluation to do so and develop a remediation plan. HEPA filters are better at removing particles from the air. The 0.3 micron diameter specification corresponds to the most penetrating particle size (MPPS) or in the worst case.
Particles that are larger or smaller are trapped with even greater efficiency. If the worst-case particle size is used, the worst-case efficiency rating is obtained (i.e., minimum efficiency values, or MERV), indicate the ability of a filter to capture larger particles between 0.3 and 10 microns (µm). EH&S recommends HEPA filters for particles and aerosols. All filters must be replaced periodically as specified by the manufacturer in the product's user manual.
If a filter is dirty and overloaded, it won't work well. With proper care and maintenance, the portable air purifier will continue to work properly and filter the air. Consider buying replacement filters with the air purifier. Carbon filters can passively absorb VOCs from the air, so make sure they remain sealed until installed in the unit to extend their lifespan.
According to the EPA, there is currently no evidence to suggest that a reasonable number of indoor plants are effective in removing significant amounts of indoor air contaminants. Indoor plants should not be overwatered because soil that is too wet can promote the growth of microorganisms that can affect allergy sufferers. Ozone, which irritates the lungs, is produced indirectly by ion generators and some other electronic air filters and directly by ozone generators. While indirect ozone production is a cause for concern, there is an even greater concern about the direct and deliberate introduction of a lung irritant into indoor air.
There is no difference, despite what some marketers claim, between the ozone found in outdoor contaminated fog and the ozone produced by these devices. Under certain conditions of use, ion generators and other air filters that generate ozone can produce levels of this lung irritant much higher than levels considered harmful to human health. The FDA could regulate a small percentage of air purifiers that claim to be beneficial to health as medical devices. The Food and Drug Administration has set a limit of 0.05 parts per million of ozone for medical devices.
While ozone can be used to reduce odors and contaminants in vacant spaces (for example, eliminate the smell of smoke from homes that cause fires), the levels needed to achieve this are above those generally considered safe for humans. Let's see what ozone is, how it could affect the body, and whether it's safe to use an air ionizer. Therefore, it is very important to consider whether the ozone produced by the typical household air ionizer is acceptable for prolonged exposure. Before purchasing an air purifier, consumers are advised to eliminate or reduce indoor sources of pollution and to ventilate areas with outdoor air.
In addition, studies have indicated that ozone from indoor air ionizers may be even more dangerous than the same level of outdoor ozone, due to direct exposure. An air purifier with a high-quality HEPA filter system removes particles from the air without producing ozone. An ionizing air purifier, known as an ionizer for short, works differently from traditional purifiers with a mechanical filter, such as purifiers of HEPA air. Most ionizers have a fan to draw air out, so the particles will be deposited on a collector plate, rather than on chairs and tables.
Many commercial ozone generators emit more than 5000 mg of ozone per hour of operation, which could result in unhealthy levels of ozone in indoor air. Skye portable air purifiers have many features that help them outperform air ionizers that emit ozone. These devices are designed to electrically charge particles in the air and cause them to adhere to room surfaces, such as walls or floors. Instead of passing air through a filter to trap contaminants, ionizers emit negatively charged ions that adhere to positively charged particles suspended in air.
Air purifiers that use electrostatic ionizers and precipitators are other types of devices that emit ozone, but they do so as a consequence of their design and function.
