What does 99.97% efficient at 0.3 microns mean?
It means that 99.97% of the particles (as small as 0.3 microns) that enter the Vornado HEPA filter will be caught and removed from the air. Particles that are smaller than 0.3 microns often attach to larger particles making them easy to capture or they attach themselves to the fibers of the HEPA media. To envision the size, line up 100,000 particles 0.3 micron in size end-to-end and it will equal one inch. For comparison, a typical human hair crosscut is about 70 microns.
