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When COVID came on the scene, air cleaner manufacturers seized the moment and revved up their marketing efforts for air purifiers. New companies also came on the market, flooding the internet with all kinds of claims about killing bacteria and viruses, removing molds, chemicals, etc.  Many of the claims were bogus but mostly ignored by regulating agencies except for a few cases like this one.

Then came an avalanche of air cleaning HVAC gadgets that homeowners could get installed in their furnace. Plasma technology, needlepoint bipolar ionization and PCO technology (Photo Catalytic Oxidation). Heating and cooling contractors got in the game and sold millions of these gadgets, some of which actually were believed to pollute the air based on research, as explained in this article.

Way before COVID, the EPA reviewed the effectiveness of most of these technologies and warned that research showed some of these devices produced their own pollutants. Additionally, we know that several schools had to remove the devices due to symptoms experienced by staff and students. One EPA article states “Bipolar ionization has the potential to generate ozone and other potentially harmful by-products indoors, unless specific precautions are taken in the product design and maintenance.”

New buzzwords abound in the air cleaning business: ionizers, electrostatic precipitators, photocatalytic oxidizers, hydroxyl generators, UV
lights, electronic air cleaning technology. Unfortunately, ANY air-cleaning devices designed to electrically charge particles during the air cleaning process have the potential to generate ozone. These can include devices that use bipolar ionization, plasma systems, ionizers or devices using UV light components at the UV-V wavelength, and devices that generate reactive oxygen species such as hydroxyl radical generators.

 Manufacturers provide their own “scientific validation”, often from questionable sources or sources with a conflict of interest, but we still lack scientifically-rigorous, peer-reviewed studies for most of these technologies. The EPA states in its 73-page document “Residential Air Cleaners” that “To date, no studies were found that systematically investigated whether using sorbent media gas-phase filtration, PCO, plasma, or ionizer air cleaners in homes or other buildings has a positive effect on the health of occupants.”

The EPA also warns that “PCO air cleaners have been shown to generate formaldehyde, acetaldehyde, nitrogen dioxide, and carbon monoxide. Plasma air cleaners have been shown to form particles, ozone, carbon monoxide, and formaldehyde as byproducts. Additionally, many electronic air cleaner devices—including portable and duct-mounted ESPs, ionizers or ion generators, uncoated UVGI lamps, and other products that advertise the use of “plasma,” “ions,” and other similar terms—can generate high amounts of ozone. Ozone is a well-documented lung irritant. Intentional ozone generators should not be used in occupied spaces“.

So what is proven to work so far? Well, as boring as it sounds, the old HEPA filtration and Carbon Adsorption filter are still the most effective and well-proven technologies to help clean the air.

For particulates like soot, drywall dust, pollens, etc… HEPA air purifiers are the best choice. A MERV11 or MERV13 furnace filter can be very effective as well. For chemical offgassing, lots of carbon is needed (or Potassium Permanganate for Formaldehyde).

Foust Company, for example, tailors the carbon in their machines to your specific needs. Austin Air has different models depending on what you need to capture. These products are made in the USA by solid manufacturers who have produced high-quality air purifiers for decades, using proven technology. When it comes to chemicals (VOCs), the more carbon the better. For example, the Foust 160R2 model has 7 pounds of carbon in a compact footprint.

And lastly, beware of another pollutant: Microwave Radiation or RF (Radio Frequencies). Many of the new air cleaners coming on the market have Wi-Fi capabilities. While more and more individuals are making a concerted effort to reduce their exposure to RF from WiFi routers, cell towers, smart meters and other wireless devices, many homeowners have an air purifier in the bedroom which, unbeknownst to them, is emitting radio frequencies non-stop near their bed! This is irresponsible on the part of manufacturers in my opinion. So, favor units that do not have WiFi capabilities or those with WiFi that can be turned off when you’re in the room.

When it comes to electromagnetic fields not all air purifiers are created equal. Some emit very high magnetic fields that extend for several feet around the unit. Keep a distance of several feet between you and the air purifier to be on the safe side.

Note: To ensure objective opinions, Indoor Environmental Testing Inc. does not accept compensation 
from manufacturers or vendors for endorsements of their products.