Reusable Pollen Filter comes in two parts: white filter and blue plastic filter housing. The two parts are integrated, and should not be taken apart. Reusable Dreamstation filters should be cleaned every 2 weeks, and replaced every 6 months or as needed. The Foam CPAP pollen filter is required to be in place prior to operate the DreamStation machine. Its purpose is to remove dust, pollen and smoke particles and enhance comfort while using your DreamStation.