Arm & Hammer (ARMCW) A& H Dirt Devil Style F22 HEPA Pkg Filter Our filters help trap 99.97% of household dust, dust mite debris, pet dander, grass and ragweed pollen down to 0.3 microns. ARM & HAMMER Baking Soda has been trusted to neutralize the toughest odors for generations, helping you create your Fresh Home For optimal performance change filter when it becomes full of dirt and dust; about every 3-6 months.