There are a lot of questions about Coway air purifiers and whether they help against the Corona virus or not.
As there are no tests done so far specifically on the Corona virus (COVID-19), there is no data to use. However, HEPA filters (which are contained in all Coway air purifiers) have been tested again and again against airborne viruses.
One organization that has frequently tested HEPA filters is NASA, which uses them in their space expeditions. They claim that HEPA filters are very effective against different sizes of particles and viruses.
How do HEPA filters work?
HEPA filters are found in all Coway’s air purifiers and, according to research, are very effective at capturing particles smaller than 0.3 micrometers. Large fiber particles are easily captured by the fiber network of a HEPA filter. Just like a fish in a fishing net, they get stuck, as illustrated in the picture below.
Coronavirus has a particle size of about 0.12 micrometers. This size of particles is called nanoparticles. They have such a small size that they bounce around when they hit gas molecules, in what the scientists call the Brownian Movement. That means they fly in a random zigzag pattern. See picture below.
Nanoparticles and viruses are very much smaller than 0.3 microns. Therefore, in theory, they should be able to easily pass through the fibers of the HEPA filter. The reason why they do not do this is because nanoparticles do not move in the same way as larger particles. Larger particles move more “straight forward”, and do not bounce around like nanoparticles do in the “Brownian Movement”. It is similar in some ways to a pinball that goes in a random direction. This principle is called diffusion.
If we find that the principle of diffusion captures nanoparticles and viruses less than 0.3 micrometers, how can we determine how effective it is in practice?
NASA claims that HEPA filters capture almost 100% of all particles. There are also many other studies that point out the same effectiveness. Studies and tests show a very good ability for HEPA filters to detect viruses and nanoparticles.
However, this should certainly not be interpreted as ensuring that Coway air purifiers eliminate all virus particles that may be present in the indoor air. Coway makes no guarantees about the effectiveness of air purifiers in filtering out the Corona virus COVID-19.