The Reusable pollen filter captures dust, pollen, mold spores, pet dander, and more wtih an 88% efficiency at 7-10 micron. The filter should be rinsed with clean tap water every 30 days. Clean with running tap water to allow the water to clear any collected debris accumulated on the filter. Only place the filter back in the DreamStation Go when completlely dry. The reusable filter should be washed every 30 days or sooner if needed.