RENPHO air purifier adopts 5-stage filtration (pre-filter, H13 true HEPA filter with coating, activated carbon filter, and net filter) can effectively remove 99.97% of particulates as small as 0.3 microns, such as allergens, pollen, dust, odors, smoke, mold, pet dander, VOCs, etc. After using RENPHO air purifiers, the air is much fresher and the allergic symptoms are significantly improved. Ideal for allergy sufferers, pet owners, and smokers!