Does UltraHEPA™ H13 filter out viruses like COVID-19?
We have many customers that are concerned about COVID-19 and the ability of UltraHEPA™ H13 to filter out this virus.
Viruses are very small at 20-400nm (ie 0.4 to 0.02 micrometers) in diameter.
HEPA filters, as defined by the United States Department of Energy (DOE) standard adopted by most American industries, remove at least 99.97% of airborne particles 0.3 micrometers (μm) in diameter. This doesn't mean that particles smaller an 0.3µm do not get caught in the filter. Our UltraHEPA™ H13 will filter viruses down to 0.003 microns.
There are three ways that particles get blocked when passing through the filter.
- The first is by impaction. Simply, the particles hit the fibers of the filter and stop like a car hitting a brick wall.
- The second is by interception. The particle tries to go around the fibers and gets it's trousers stuck on the door knob.
- The third mechanism is by diffusion. Nano-particles move by what is call Brownian motion meaning that they collide with one another on a constant basis causing a zig-zag motion. This motion causes them to get stuck as they collide with one another and diffuse into the fibrous network and get stuck.
It is through this last mechanism that the smallest of particles such as viruses are caught by a filter that has holes larger than the particle that gets stuck.
The COVID-19 virus may not be completely blocked by UltraHEPA™ H13 filtration system. However, a single UltraHEPA™ filter has greater than 95% effective against very small nano-particles like viruses.
Finally, multiple layers of filters, such as our system increases filtration simply because there are more opportunities for nano-particles to get stuck in the fibers.
To see a summary about these facts go to the American Society of Hospital Engineering COVID-19 FAQ page and click on "Filtration".