Ionization devices—known as bipolar ionization, needlepoint bi-polar ionization, ionizers, photohydroionization, or electronic air cleaners—are currently being widely used in efforts to clean the air and prevent the spread of COVID-19. School districts, in particular, have invested hundreds of thousands, if not millions, of dollars in the equipment. Now, a growing chorus of experts say ionization is an unproven—and potentially harmful—waste of money.  

On April 12, 2021, a “who’s who” of experts on the spread of infectious disease signed on to an open letter advocating against the use of electronic air cleaning equipment—in the same letter they do recommend germicidal ultraviolet light (UV or UVGI).  As noted in the letter, because ionization devices “are unproven, it is critical to avoid wasting valuable emergency COVID relief aid dollars installing them within school district facilities.” The subject was also addressed in the March 26, 2021, Wired.com article: “The Ionizer in Your School May Not Do Much to Fight Covid.” Moreover, in a seminal study recently published in the journal Building and Environment, independent testing by an experienced lab showed that bipolar ionization did not significantly impact particle concentrations—in other words, it did not remove virus from the air. (Reference)

Crucially, not only do the experts in the open letter advocate against the purchase of electronic air cleaning devices, they advise those who have already installed ionization equipment to turn it off: “Despite the resources invested, we recommend that these districts strongly consider turning off or disabling these electronic air cleaners to prevent unintended harm to building occupants.”

How does bipolar ionization work? 

Simply put, ionization captures particles from the air and settles them down on the ground (or objects before they hit the ground which could include people and high-touch surfaces). UVGI, on the other hand, works by killing pathogens in the air as they pass by the germicidal ultraviolet light. More on the ionization process from the Wired.com article:

“The ions are meant to induce what chemists call ‘coagulation.’ Like blood cells clotting a wound, particles of opposite charge glom together, capturing nasty things that you don’t want in your lungs, like pollen and mold. Eventually, those clumps grow large enough that gravity takes over and they fall harmlessly to the ground. With viruses, there’s another benefit: The ions gum up surface proteins used to enter cells, making them less effective invaders. The result, and the banner claim made in the company’s pitch to schools during the pandemic, is a 99.92 percent reduction in coronavirus within 30 minutes. The problem, according to air-quality experts, is that there’s little independent evidence to back up such claims.”

Needlepoint bi-polar Ionization vs. UV light—what the authoritative organizations say

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) does not recommend ionization. Same goes for the Centers for Disease Control and Prevention (CDC). More specifically, ASHRAE doesn’t have a society opinion on the technology, instead, referring to the CDC’s position which says that “relative to many other air cleaning or disinfection technologies, needlepoint bi-polar ionization has a less-documented track record.”

On the other hand, both ASHRAE and the CDC have recommended UVGI as a technology to help prevent the spread of certain infectious pathogens, including SARS-CoV-2, the virus that causes COVID-19. As recommended in the CDC’s ventilation guidance for reducing exposure to SARS-CoV-2:

“Consider using ultraviolet germicidal irradiation (UVGI) as a supplement to help inactivate SARS-CoV-2, especially if options for increasing room ventilation are limited. Upper-room UVGI systems can be used to provide air cleaning within occupied spaces, and in-duct UVGI systems can help enhance air cleaning inside central ventilation systems.”

This was also referred to in the CDC’s guidance for reopening schools. The CDC also suggests UVGI for other diseases such as tuberculosis: “Research indicates that an appropriately designed and maintained upper-room UVGI system may kill or inactivate airborne TB bacteria and increase the protection afforded to healthcare workers while maintaining a safe level of UVGI in the occupied lower portion of the room.”

Similarly, ASHRAE recommends UVGI in multiple instances in its position document on airborne infectious diseases. It finds UVGI one of its “strategies of interest” and, in describing pandemics even prior to the current one, noted that upper room UVGI could be used in emergency rooms in a variety of high-occupancy indoor environments. Also, in describing the fact that “some infectious diseases are transmitted through inhalation of airborne infectious particles, which can be disseminated through buildings by pathways that include ventilation systems,” ASHRAE includes UVGI as a way to reduce airborne infectious disease transmission.

The takeaway from authoritative opinions: UV is a proven technology, ionization is not.

Ionization may produce harmful byproducts

Just like the fact that not all UV is the same, all ionization equipment is not the same. Nevertheless, some general conclusions may be made. In the open letter the following is described:

“For example, one recent independent test (ref:2) of needlepoint bipolar ionization (NPBI) technology found that the strength of the ions produced appears insufficient to effectively clean the air, and the device also produced VOCs. Another study (ref: 4), conducted by The Bureau of Toxic Substance Assessment (BTSA), monitored indoor air quality (IAQ) in a high school classroom and characterized changes in IAQ resulting from a bipolar ionization (BPI) unit operating in the air handling unit serving the classroom. Higher levels of ozone and ultrafine particles were measured, indicating that IAQ worsened with the ionization device in operation. Both of these studies also raise serious concerns about the unintended byproducts produced from these electronic cleaning devices, which are typically neither studied nor reported by the device manufacturers.”

See also “Study: Ionization Air Purifiers May Create Harmful Pollutants.”

By contrast, Aerapy UV does not produce ozone, data recently confirmed during independent lab testing against SARS-CoV-2 in which Aerapy UV achieved a greater than 99.9% kill rate against the virus. In addition to SARS-CoV-2, Aerapy UV has been tested against a variety of other viruses and bacteria and achieved the same high kill rates.

Money wasted on unproven technology

Prior to the current spate of criticism, ionization, for the most part, enjoyed positive PR in popular culture. Few of us are not familiar with ionizing devices—personal-sized ones have been widely available for years and, perhaps, along with flashy marketing, there was a level of personal familiarity baked in when decisionmakers for schools and other public buildings poured money into unproven technology over the past year. Quoted in the Wired.com article, an air quality consultant lamented: “It’s so cheap to use current proven technologies…There’s so much misinformation.”

UVGI is a proven technology that has been utilized for over a century to help stop the spread of infectious disease. Commonly used in hospitals and government buildings, UV has also been a fixture in schools, perhaps most famously in the 1930s when upper room UVGI helped stop the spread of measles. As laid out in “The History of Ultraviolet Germicidal Irradiation for Air Disinfection”: “There is a long history of investigations concluding that, if used properly, UVGI can be safe and highly effective in disinfecting the air, thereby preventing transmission of airborne infections.”

UV is affordable

Included in their plea to schools to not install ionization equipment—and, if they have installed it, to turn it off—the open letter experts also touch on the affordability of UV:

“Following the precautionary principle, we must advocate for schools not to use electronic air cleaning devices. The proven measures that should be taken to address airborne transmission risk include properly sized and maintained ventilation (mechanical and natural), mechanical filtration (including portable HEPA filter units), and germicidal ultraviolet light systems. Such measures are practical and often can be easily implemented; many are not costly, particularly when assessed on a per student basis. Even without the relief aid dollars many are inexpensive enough to be funded with capital outlay dollars instead of passing a bond.”

Aerapy UV is affordable. Because we know one size does not fit all, we approach each project individually. To learn more about our proven UV technology, including our patented UV devices, and for a custom price quote, contact us today.