My gaze fell on my air purifier this morning, the unit I bought to keep seasonal wildfire smoke under control in my house. It's the same model as the one in the photo. It uses three filters, one of which is the Hepa type.
That got me wondering whether these appliances were of any use in the Covid-19 contagion. Before you go in search of a purifier, it probably won't do you much good. The Hepa filter is effective against the virus particles.
The virus that causes COVID-19 is approximately 0.125 micron (125 nanometers) in diameter. It falls squarely within the particle-size range that HEPA filters capture with extraordinary efficiency: 0.01 micron (10 nanometers) and above.That doesn't mean it will keep you safe and secure.
But that doesn’t mean an air purifier can protect you. While scientists are still researching how the new coronavirus spreads, the current consensus is that it is not an airborne virus, and that’s the position of both the CDC and other global health agencies. Rather, experts believe that the coronavirus is transmitted by person-to-person contact and by contact with virus-laden droplets expelled by an infected person’s coughing and sneezing. Coughs and sneezes certainly suggest “airborne” to most people, but such droplets travel only about 6 feet before falling out of the air and settling on surfaces. This is one reason health agencies worldwide are recommending 6-foot (2-meter) “social distancing” and related efforts like frequent handwashing and disinfection of surfaces as the primary means of protecting yourself.In other words the Covid-19 infection probably won't happen in your own home. It's an "outside" thing.
Just thought you might want to know.