What is HEPA?
A HEPA (High Efficient Particulate Air) filter is a throwaway, extended-medium, dry type filter in a rigid frame having a minimum particle collection efficiency of 99.97% (that is, a maximum particle penetration of 0.03%) for 0.3-micron particles.

What is ULPA?
An ULPA (Ultra-Low Penetration Air) filter is a throwaway, extended-medium, dry type filter in a rigid frame, having a minimum particle collection efficiency of 99.999% (that is a maximum particle penetration of 0.001%) for particles in the size range of 0.1 to 0.2 micron.

What is a Micron?
A Micron (?) is a unit of measure, used by the cleaning industry to describe particles that are extremely small
One micron = 1/25,000 in.
A human hair averages 70 micron
Bacteria is .4 to 10 micron
Mold is 1.2 to 90 micron