1. A newly renovated or renovated residence. 2. There are residences for the elderly, children, pregnant women, and newborns. 3. Residence for people with asthma, allergic rhinitis and pollen allergies. 4. The residence where pets and livestock are kept. 5. Houses that are relatively closed or affected by second-hand smoke. 6. Hotels, public places. 7. A residence for people who are willing to receive a high-quality life. 8. In hospitals, reduce infections and prevent the spread of diseases.