high efficiency particulate air (hepa) filter for Dummies
As an example this, consider that 1 micron is just one-millionth of the meter, which may be about a hundred th the width of a human hair (depending upon the person, certainly). A particle under 10 microns is invisible into the naked eye, so You can't precisely see the HEPA filter working.Look through Henle's loop henley henna henpecked HEPA filter