Blueair Blue 3410 Air Purifier Replacement FilterThe particle filter layer minimises the airborne particles that can trigger allergy symptoms, including pollen, dust, mould spores, pet dander, viruses, bacteria, and fine smoke particles. The layer of activated coconut carbon absorbs light gases, including volatile organic compounds (VOC), smog, chemicals, and unwanted household odours from pets, smoke, and cooking. Depending on your environment, you must replace the combination filter every 6 months