By Greg Rankin
The average person spends about 90% of their lives indoors. Whether at home, work, or school the need for pollution- and pathogen-free indoor air has become a matter of public health. While the number of air cleaning devices on the market increased during the pandemic, many technologies were deployed before hard data could demonstrate both their safety and effectiveness. Now researchers have done their due diligence and are revealing some of the hidden hazards behind many air cleaning technologies.
In fact, research from Dr. Jose Jimenez – a professor at the University of Colorado and fellow of the American Association for Aerosol Research – demonstrated that many air cleaners in the marketplace today actually increase mortality rates by emitting excess pollution. In the study, which was revealed in a webinar put on by the EPA, Dr. Jimenez looked at air cleaner technologies and their capacity to disinfect pathogens within indoor air compared with their proclivity to produce ozone and fine particulate matter (PM).
“During the pandemic, everything was in a hurry,” explained Dr. Jimenez. “Now we have had time to digest the information, so we should prioritize creating standards so beneficial air cleaners can be deployed.”
The study’s findings were startling for many and illustrate the urgent need for either new air cleaning technologies or a combination of existing devices that can clean and disinfect indoor air without emitting pollution.
“The worst thing we can do is trap the air inside with the virus and the pollutants and not do much about it,” added Dr. Jimenez. “That is not very smart, but unfortunately, it’s what we do most of the time and it has significant health effects.”
Airing It Out
Air pollution is one of the leading preventable causes of death worldwide according to the World Health Organization (WHO). While Dr. Jimenez’s research showed that most air cleaning technologies disinfect the air, to varying degrees, they also emit ozone and fine particulate matter. These pollutants have been linked to serious health impacts, including chronic bronchitis, asthma, and premature deaths.
The research, titled “Health Benefits vs. Disbenefits from Indoor Air Cleaners,” broke down air cleaning technologies into two categories. The first group of devices attempts to remove the pathogen, and some pollutants, via filtration. Technologies in the other group were strictly focused on disinfection. In this case, the pathogen remains in the room but is deactivated or killed.
“Most of the air cleaners we tested only protect us from extreme situations, but they really don’t do much good,” explained Dr. Jimenez.
The study did not include any brand names, but instead looked at the different air-cleaning technologies. Those that were inspected include HEPA, activated carbon filters, electrostatic precipitators, ozone generators, hydroxyl generators, photocatalytic oxygenation, ionizers, bipolar ionizers, germicidal ultraviolet (UV) at 222 and 254 nanometers.
Near the bottom of the list, in a category Dr. Jimenez recommends be avoided, include ozone generators, hydroxyl generators, photocatalytic oxygenation, ionizers, and bipolar ionizers.
“Ozone generators should absolutely never be used around people, no matter how bad the pandemic,” explains Dr. Jimenez. “Hydroxyl generators are pollution-making machines. I was shocked to find companies are selling these as air cleaners.”
Sifting Through The Science
There were some technologies that demonstrated better results. For example, activated carbon filters do remove PM and ozone when enough activated carbon is present within the device. Unfortunately, most of the commercial air cleaners tested only had a small amount of the required substance.
High MERV-rated HEPA filters, which offer a 99.9% efficiency rating when it comes to collecting small particles and pathogens, also showed promise within the study. They offered some of the lowest mortality statistics in the study due to their emissions. However, in real world scenarios virologists worry about HEPA filters because they do not deactivate viruses or kill bacteria.
“Because HEPA filters merely capture pathogens and focus them in one place, the chance that any collected pathogens could be still spread remains. For example, when changing the filter,” explains Dr. Frank Scholle, Associate Professor of Biological Sciences at NC State.
UVC technology also delivered lower mortality rates from the air pollution they created and showed good disinfection capabilities in deactivating pathogens. However, ultraviolet light can cause adverse health effects, such as headaches and skin cancer, in individuals who are over-exposed.
Utilizing UVC within air ducts and away from people could offset those drawbacks, but Dr. Jimenez warned that doing so would likely increase the chances of a failure going unnoticed. There are also concerns about operational and maintenance expenses which can be significantly impacted due to higher power requirements and costly bulb replacements.
Overall, the study was unable to find what Dr. Jimenez calls “a silver bullet” solution. He did, however, suggest the possibility of combining some of these technologies to control both pollution and infectious airborne diseases, but notes that this would likely drive-up costs.
Breathing Easy
With more funding, Dr. Jimenez hopes to review newer air- cleaning technologies that have shown promising results. For example, a new filtration technology, called SPAR (Smoke and Pathogen Air Removal) — formerly known as FIL-TEX – has been proven to be effective against airborne pathogens. In a recent third-party efficiency test, CREM Co Labs – an independent laboratory in Canada specializing in testing for the infection prevention and control (IPAC) industry – recently published its assessment of SPAR Filters.
The report authored by Dr. Bahram Zargar – an expert in virology and microbiology – demonstrated that the SPAR filter can effectively remove 99.92% of airborne viruses, and 99.99% of airborne bacteria, while deactivating 98% of viruses found on the filter’s surface. The testing was done utilizing a large, 26 cubic meter aerobiology chamber.
“This device takes the best performance characteristics from passive technologies – like HEPA, that capture particulates – and active technologies – like UVC, that purify air – and combine them into a single, thin, lightweight air cleaning solution,” explained Dr. Scholle.
The innovative technology takes electrodes made up of stainless-steel yarns and embeds them onto non-conducting yarns – like cotton, polyester, Kevlar, or even recycled plastic. This creates a non-thermal plasma field on the surface of the textile media which operates like a magnet, attracting and then deactivating unwanted contaminants from the air.
In addition, the technology does not emit any additives or substances into the air and meets all NIOSH and OSHA standards for ozone.
Clearing The Air
“Does it cause pollution deaths, I think that should be the number one thing to consider about any air cleaning device,” concluded Dr Jimenez. How well it disinfects, and the overall costs are also important considerations.
The study did not take into account the cost of the devices, maintenance requirements, the cost of electricity, or the generation of waste – like consumable filters – in their analysis. As more testing is completed, more data will be made available to the public.
Greg Rankin is a Houston-based freelance writer with more than 20 years of experience writing about the HVAC industry, mechanical engineering, and clean technology.
