It is advised to wear a anti-pollution mask when are outside.
I recommand Totobobo. It is efficient and filters 100% of micro particles pm2,5.
In China, many Chinese people wear 3M masks. However these masks can be used only once. This is not very convenient.
I also bought a Respro mask. It is efficient but far too expensive as you should change the expensive filters every two weeks...
I wanted to show you how Chinese people react when they see me wearing this mask.