If you need to take off the mask outside, you should not put it into your coat pocket for storage. If you buy a single packaged mask, you can keep the original packaged bag and store it in the original packaged bag after taking off the mask by folding it (inside of the mask facing inward); if you use multiple packaged masks together, you should have a cleaning bag with you and store it in the cleaning bag after taking off the mask. If you do not have a cleaning bag, you can use two paper towels: first lay a paper towel flat, put the mask on it (note that the outside of the mask is down), and then cover it with a paper towel. This will keep the inside of the mask clean and prevent contamination from the mask being placed in your coat pocket, and ensure that it does not become deformed.