HEPA Filter Air Purifiers
A HEPA air purifier has a HEPA filter which can trap a large
amount of small particles. True HEPA filters must be able to trap at
least 99.97 percent of particles down to 0.3 microns, or 1/100th of
a human hair. For more buying advice, see our editor's picks for
best HEPA air purifiers.
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What is a HEPA Filter?
The HEPA filter was developed during World War II by the Atomic Energy Commission and it was designed to remove and capture radioactive dust particles from the air which might escape and present a health hazard to the researchers. HEPA filter was specifically designed to protect the Human Respiratory System. Even the CDC guidelines for the transmission of tuberculosis (TB) recommend that only HEPA filters with an efficiency of 99.97% tested at 0.3 microns particle size or smaller be used.
What's a Micron?
A micron is a measure of length: "1 micron equals 1 millionth of a meter!".
A particle that is 10 microns or less in size is not visible to the naked human eye.
Is 0.3 Microns Filtration Important?
YES!
Particles that are 0.3 micron in size
are the most difficult particles to trap and contain within a filter. Also,
0.3 micron particle, when inhaled,
passes easily into the body's respiratory system so the body's natural defense
system is more vulnerable to these small particles. This is why
ONLY HEPA filters are
recommended by Allergists and Doctors..
Should I leave my HEPA air cleaner on all of the time?
YES! Leaving the unit ON even when you are away lets the unit constantly scrub the air. Also, if a unit is turned off for a long period of time and then turned back on, you may smell some of the captured particles within the HEPA and or carbon. You should ALWAYS leave a HEPA unit running 24/7. If you do turn it off for days and weeks you are best to also change the filters. Most people's reasoning for turning it off is to save on electrical costs. This is why an energy efficient blower motor (low wattage) is the best!
Does a higher wattage unit mean stronger fan motor?
NO! The higher the wattage simply means the higher in electrical costs to run. High quality and High-End HEPA air cleaning units do not use lower cost, high energy using fan motors. Energy efficient motors are available but at a higher cost to purchase. Also, most High Quality Fan Motors are also quieter! A portable HEPA Air Cleaner with a quality energy efficient fan motor should be in the area of 80 to 200 Watts MAX at 350 to 600 CFM.
Examples of some common air contaminants and their size in microns:
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Human Hair ......................................... (70 - 100 microns)
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Human Sneeze ................................. (10 - 100 microns)
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Pet Dander .......................................... (0.5 - 100 microns)
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Pollen ................................................... (5 - 100 microns)
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Spores from Plants .............................. (6 - 100 microns)
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Mold...................................................... (2 - 20 microns)
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Smoke ................................................... (.01 - 1 micron)
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Dust Mite Debris ................................. (0.5 - 50 microns)
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Household Dust ................................. (.05 - 100 microns)
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Skin Flakes ........................................... (0.4 - 10 microns)
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Bacteria................................................. (0.35 - 10 microns)