HEPA is an acronym for "high efficiency particulate air". Basically HEPA is a type of filter that can trap a large amount of very small particles that other vacuum cleaners would simply recirculate back into the air of your home. There are a couple of different categories of HEPA filters that can make understanding the abilities of your filter confusing.
True or Absolute HEPA Filters
True or absolute HEPA filters must pass a test to be considered HEPA worthy.
True HEPA filters will have a serial number assigned to them if they are able to trap at least 99.97 percent of particles of .3 microns. These test results will be printed on the filter. True or absolute HEPA filters may be more expensive than other HEPA filters, but they must perform at a certain standard to receive the distinction of true or absolute HEPA.
HEPA Type Filters
HEPA type or HEPA like filters may be made in similar ways to true HEPA filters and may even resemble them. They do not have to meet the same standards as true or absolute HEPA filters. They often capture only 85 to 90 percent of particles and that percent can fall even lower for particles of 1 micron and below. HEPA type filters are less expensive than true or absolute HEPA filters.
Telling the Difference
Look for the serial number and test results printed on true or absolute HEPA filters. Make sure that the test results at .3 microns are 99.97 percent or above.
The size of .3 microns is the testing standard, because most filters will perform better with both smaller and larger particles. Double-check the test results at .3 microns to make sure your filter is a true or absolute HEPA.
Why Buy a HEPA Filter
HEPA filters trap small particles that may cause problems for allergy sufferers and others with health problems.
Reducing or eliminating those particles will make cleaner air for the residents of your home. Decide if a true HEPA is necessary for your family, or if capturing a smaller amount of particles is worth the price break on filter costs.