ifD (Intense Field Dielectric) is a breakthrough, permanent filtration method that is highly effective in helping to remove airborne particles at a 99 percent efficiency level. Early adopters of ifD technology Leading the Industry in Advanced Air Purification. ifD filters are permanent and washable air purification filters that are starting to be used in home air purifiers. The Air Genius iFD filters capture 99. Honeywell QuietClean Tower Air Purifier with IFD Filter You dust, you mop, now help your air.