Air Purifiers That Don't Use Filters

Electrostatic Precipitators

• Air purifiers that rely on electrostatic precipitation use electricity to add a charge to particles of pollution as these pass through the device. The charged particles are attracted to a metal plate within the air purifier. Once the particles collect on the surface, users can simply remove the plate and wash away the particles, then replace the collector for reuse. While this technology removes particulate matter, odors, gases and allergens from the air, the California Environmental Protection Agency warns that electrostatic precipitation generates some ozone as a byproduct. Ozone is a toxic gas consisting of three oxygen atoms, which is linked to ill health effects at high concentrations.

Ionizers

• Ionizers, or ion generators, produce charged ions and distribute them into a room. Once in the air, the charged ions attach to pollution particles and bond together. Eventually, they clump together and fall to the floor or settle on walls, furniture and other surfaces. These units can remove particulate matter, some viruses and bacteria, and tobacco smoke, according to the Home Depot. Like electrostatic precipitators, ionizers produce some ozone as a byproduct. Another drawback to these units is that they deposit dust and particles on surfaces in the home, which could increase cleaning time.

Ozone

• Though some air purifiers produce ozone as a byproduct, some filterless air purifiers are actually marketed as ozone generators. These devices use ultraviolet light, electric charges or some combination of the two to generate ozone molecules to clear the air. While ozone generators can help transform biological and chemical pollutants into harmless substances, these appliances pose significant health effects. The U.S. Environmental Protection Agency warns that appliances that produce enough ozone to effectively clear the air are generally harmful to the health of occupants. Ozone, which is linked to lung damage, eye, nose and throat irritation, may also trigger asthma attacks. The California EPA recommends avoiding ozone generators, particularly if you have children, elderly family members or anyone with a compromised immune system living in your home.

Ultraviolet

• Ultraviolet air purifiers emit UV radiation to kill biological contaminants like viruses, bacteria, mold and mildew. While this technology shows promise, the EPA suggests that most home UV purifiers are relatively ineffective due to the low levels of UV radiation they emit.

Photocatalytic Oxidation

• Air purifiers that rely on photocatalytic oxidation use UV light and a catalyst, such as titanium oxide, to clear the air. The light and the catalyst combined react with gaseous contaminants to render them harmless without actually removing them from the air. Like UV purifiers, PCO models are relatively ineffective, according to the EPA, but research by the Lawrence Berkeley National Laboratory shows potential promise for PCO air cleaners in the future.