In past blogs we discussed the fact that you can only see down to about 20 microns in size with the naked eye.  For comparison, your hair is about 100 microns in diameter. Dust particles that you see floating in the air are around 100 microns and larger. The larger particles are too heavy to stay airborne so they tend to fall on the floor or other surfaces. 

Airborne allergens such as pollen, ragweed and grasses can also be airborne and they can be smaller than 20 microns in size and stay airborne for a period of time. Allergy sufferers know this all too well. Bacteria can be as large as 10 microns and smaller than 0.3 microns. Bacteria can be on any surface and stay airborne for long periods of time. Viruses, on the other hand, are extremely tiny, as small as .005 microns or 1/1000th of an inch. They can stay alive and airborne for hours both indoors and outside. Covid -19 is a virus.

Removal of airborne particles (both organic and inorganic ) is done best using media style air filters ( think furnace style filter ) that can capture these particles and remove them from the air. For larger dust particles the furnace filters or Merv 7-9 rated filters, are adequate in capturing 90% of the larger dust particles. But less than 10% effective in capturing bacteria or viruses.

Removing these tiny particles requires a HEPA filter. These High Efficiency Particulate Air filters are designed for the commercial, medical and institutional markets and now also used in the residential markets. A standard, true, HEPA filter is rated at 99.99% efficiency for particles 0.3 microns or larger and is over 95% effective at removing particles particles less than 0.005 microns in diameter. Some HEPA filters use a more dense media and are called ULPA  ( Ultra Low Particulate Air) or SULPA ( Super Low Particulate Air ) filters. These are designed for applications like the CDC and micro chip manufacturers.

For more information on HEPA filters and their capabilities go to our website at:   http://www.pureairsystems.com  or call us on our toll-free number at 800-869-8025.




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About the Author: Don Musilli

My name is Don Musilli. I started Pure Air Systems in 1985 and then sold it in 2006. I continue to consult for PAS and write their blog and control their Twitter account. I also, on occasion, make changes to the website. The company is now almost 26 years old and has been a major player in offering commercial grade, high performance HEPA and Carbon based filtration systems for the commercial, institutional, industrial and residential markets.

I currently reside in Englewood, Florida where I write blogs and do social media marketing for a number of clients.


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