First-layer Filter: Filters dust particles of 5 microns and larger, such as large dust, dandruff, pollen, human hair, and pet fur. Composite Activated Carbon Filter: Effectively absorbs odors, smoke, chemicals, and toxic gases harmful to the body, such as benzene, toluene, xylene, formaldehyde, and ammonia. HEPA Filter: Captures particles as small as 0.3 microns with 99.97% efficiency, such as dust, bacteria, smoke, pollen, mold spores, pet dander, dust mites, cockroach allergens, and various viruses. It can also filter bird flu, human flu, and Legionella bacteria.