Surround Air Multi Tech Spare HEPA Filter for XJ-3000 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. The Atomic Energy Commission developed HEPA air filters during the Second World War. They were originally designed to remove radioactive dust from their plants. The U.S. Dept. of Homeland Security recommends HEPA air filters. HEPA air filters are effective for solid and liquid particles, but not effective for gaseous particles. The XJ-3000C HEPA & ionic air purifier incorporates other technologies that are effective against gaseous particles, such as ionization and activated carbon filtration.