Hepa is a type of pleated mechanical air filter. A hepa filter would follow the same filtration principles but. Hepa Filters And Ulpa Filters Selection Guide Engineering360 A standard air filter usually eliminates medium to larger particles from the air however they do not have the capabilities to almost completely eradicate tiny micron size particles from the air as a hepa does. Hepa filter particle size . All en 1822 specifications are based on a filters ability to trap and contain the most penetrating particle size mpps particular to the filter. Because particle size has a direct impact on the specific type of air purifier and filter you need. The filter efficiency chart below figure 1 represents a filter that is approximately 90 efficient against a range of particle sizes. This type of air filter can theoretically remove at least 9997 of dust pollen mold bacteria and any airborne particles with a size of 03 microns um. A ...