Surround Air Intelli-Pro Spare HEPA Filter for XJ-3800 Series Air Purifier
HEPA air filters are made from very tiny glass fibers that are made into a tightly woven paper. This creates a filter consisting of a multitude of very small sieves that can capture extremely small particles, including some biological agents. Once trapped, contaminates and particles are not able to flow back into circulation, due to the highly absorbent pores of the HEPA air filter.  HEPA air filters are largely considered the most effective type of air filter for solid particles, such as dust and other allergens. HEPA air filters remove 99.97% of particles down to 0.3 microns in size, almost 300 times smaller than the width of a human hair. HEPA air filters were developed by the Atomic Energy Commission during the second World War. They were originally designed to remove radio active dust from their plants. HEPA air filters are recommended by the U.S. Dept. of Homeland Security. HEPA air filters are effective for solid and liquid particles, but not effective for gaseous particles. The XJ-3800 HEPA & ionic air purifier incorporates other technologies that are effective against gaseous particles, such as ionization and activated carbon filtration.