More than six months after the first outbreak of COVID-19, we’re still learning about how the coronavirus is transmitted. We know that it’s often conveyed by coughing and sneezing, that it can exist for extended times on certain surfaces, and that it has at least some transferability through the air. But there’s still plenty of mystery in how COVID-19 can be restricted or contained.
Air quality is one factor the coronavirus has caused many people to think about. Respiratory issues are a very common symptom of COVID-19. Since it has some airborne properties, a common question is how much of an effect various air filter appliances and techniques may have in controlling its spread.
The answer, though, is still incomplete. Although air filtration systems and methods regularly undergo testing for their efficiency against several of the most prevalent contaminants and particles, most of them haven’t been tested specifically for effects on COVID-19.
Scientists and researchers, therefore, rely on data involving viruses that may be quite similar to the coronavirus but cannot yet offer definitive answers about how COVID-19 itself reacts with air filtration systems. They can, however, make a few highly educated guesses based on what they do know.
Although these air filtration methods may help mitigate the risk of the coronavirus, it’s important to note that as of now, none of them are solutions or cure-alls for those already suffering from the virus. But there’s a chance—possibly—that they can lessen the hazard.
High-efficiency air filters (HEPA)
High-efficiency particulate air (HEPA) systems are extremely effective at filtering out dust, allergen, mold, and other particles as small as 0.3 microns. A true HEPA system traps those particles at an impressive rate of 99.97% efficiency.
The COVID-19 virus is 0.125 microns in size—too small, by more than half, for what a HEPA system can trap. However, one of the coronavirus’s main means of transmission is through considerably larger moisture droplets—potentially as big as 1 full micron. That’s enough for a HEPA filter to catch. Even so, there are a lot of variables that affect how well the filter works (including that the droplets must somehow travel to the filter in the first place).
Overall, HEPA systems may have a minimal mitigating effect on COVID-19 in certain environments, but the answer is far from definitive at this point. (Low-efficiency air filters, if you’re wondering, likely have little effect, if any.)
Electronic air filters and ozone generators
Electronic air filters work by channeling extra-small particles into a layer where they’re electrically charged, then transmitted into another layer of substances with the opposite charge. Some electronic filters also contain ozone generators, which eliminate certain contaminants like mold and bacteria.
Ozone generators can eliminate up to 99% of virus cells—including SARS—when given enough time and exposure to the air to work. However, there’s a massive respiratory risk to humans with ozone air purifiers (they’re illegal in some states), and as with all other systems, specific tests with COVID-19 have not yet been possible. Even if it’s proven that they work on the coronavirus, ozone filtration systems aren’t recommended.
Ultraviolet (UV) lamps are often used in air ducts and concealed air ventilation systems to kill viruses. They’ve been shown to work on viruses like SARS and MERS.
The catch is that UV lights require a considerable amount of time to kill the DNA structure of the viruses; if a virus travels too quickly across the area a UV lamp covers, it will escape. Also, since excessive UV exposure also poses a health risk to humans, they’re not recommended for continuous use anywhere other than a closed-off, inaccessible area, like an air duct.
Theoretically, a UV lamp can kill the COVID-19 virus, but it hasn’t been firmly proven yet. Even so, the virus’s mobility means it probably can’t stay still long enough for the UV light to eliminate it. Since UV lamps are tools too dangerous for humans to use in communal areas, they can’t be recommended as COVID-19 solutions.
Air scrubbers work by sending purified, oxidized molecules into air currents, where they eventually attach themselves to contaminants. One advantage with air scrubbers is that they don’t wait around for particles to arrive—they send their killer particles out into the world to proactively attack poisoned particles. A few air scrubbers also use UV light in certain applications. These factors also make air scrubbers very expensive, perhaps too prohibitively so for some.
Air scrubbers are proven to work on many viruses and impurities, including E. coli, strep, and strains of avian and swine flu. However, as you may have guessed, their effectiveness against COVID-19 remains untested. Theoretically, they may end up being remarkably successful in neutralizing the coronavirus—but as with all the methods in this post, we still need to learn more before making a true declaration about how effective they are against the coronavirus.