What situations is it recommended to wear KN95 face masks?

What situations is it recommended to wear KN95 face masks?

1, When you go to hospital to see a doctor, or accompany with your family of friends to see a doctor, or pick up medicines from medical institutions .

2, When you visit elderly persons, infants, or the patients with underlying diseases. 

3,When you conducting nucleic acid testing, receiving takeaway and parcels from carriers .

4,When you are at a confined spaces with poor ventilation condition and bad air circulation,such as elevators,metros,buses and so on . 

5, When it’s difficult to judge the risk, but you still need to closely communicate with strangers, such as door-to-door service from maintaince persons and decoration persons , communicating with sales.