If it is used for prevention and control, it is more appropriate to use a medical surgical mask. If you are going to an open public place and not in contact with the patient, such as to a park or going out for sports, running, or playing ball, you can choose to wear a medical surgical mask without excessive protection. Because in a relatively open environment, the risk of viral infection is relatively low. If you are a medical worker or are likely to come into contact with suspected patients or patients with respiratory infections, you should try to wear a medical N95 mask. And the general mask should be replaced within 4 hours, if only worn 1-2 times and for a relatively short period of time, it can also be used multiple times, but the overall length of time is best not to exceed 4 hours. If one is exercising alone in a very open place, or without contact with other people, it is perfectly fine not to wear a mask. Content source: Dr. You Lai