The term "HEPA" stands for High Efficiency Particle Airification. The H.E.P.A filter is a pleated type filter whose only function is to remove particles from the air (dust, smoke, pollen etc.) Normally the H.E.P.A type filters uses large amounts of adhesives to seal off the ends of the pleated material. The sealant required can out-gas and cause people to have a bad reaction, especially those who are chemically sensitive or have asthma or other allergies.
Aireox particle filters do not require adhesives that can outgas chemicals into the air.