Smart Air SA600 Air Purifier Replacement Carbon Filters (2-Pack)The Smart Air SA600 air purifier uses carbon filters to remove harmful gases and unpleasant odours such as formaldehyde, benzene, smoke, and bad smells. The lifespan of the carbon filter for the SA600 air purifier depends on the air quality in your environment. Typically, it should be replaced every 4 6 months. However, if the air quality around you is poor, you may need to replace it more frequently.