What are HEPA Filters
HEPA is the abbreviation for High Efficiency Particulate Air. Many modern air cleaning devices and vacuum cleaners use a HEPA filter to remove almost all dust particles up to 0.3 micrometers (µm) in diameter. The human hair measures between 17 to 181 µm in diameter.
Wikipedia describes the function of HEPA filters in vacuum cleaners as follows:
HEPA filters are beneficial for asthma and allergy sufferers, because the HEPA filter traps the fine particles (such as pollen and dust mite feces) which trigger allergy and asthma symptoms. For a HEPA filter in a vacuum cleaner to be effective, the vacuum cleaner must be designed so that all the air drawn into the machine is expelled through the filter, with none of the air leaking past it.
This is often referred to as "Sealed HEPA" or sometimes the more ambiguous "True HEPA." Vacuum cleaners simply labeled HEPA have a HEPA filter, but not all air necessarily passes through it.
Finally, vacuum cleaner filters marketed as "HEPA-
