Your filter has been doing such fine job but all good things come to an end. The warning light is there. Get yourself a replacement filter. Keep your air purified as it should be. Five layers. Pre-filter for large particles. HEPA filter to get dust mites, smoke and more. Activated carbon filter to get chemicals and volatile organics. Cold catalyst filtration for compounds such as benzene. Negative ions for allergens and germs. Open the lid. Pull out your old filter and dispose of it in the bin. Slot your new filter in. Close the lid. Bingo. You are now ready to filter your air again. Buying a filter is an investment in your health. If you live near a main road or construction site, you will know exactly what I am talking about. Your filter will catch all that dust.