What does 99.97% HEPA filter mean?
HEPA means High Efficiency Particulate Air. These filters will catch 99.97% (almost 100%) of particles as small as 0.3 microns and larger. These are made of 100% micro-fiber glass media. If 10,000 particles of size 0.3 micron and larger are forced through the filter an average of only 3 particles would pass through the filter.