Breathing valve does not affect the protection effect of the mask for general users. A mask with a breathing valve makes the airflow unidirectional to the outside, so the virus will not “take advantage of the situation” through the breathing valve, it does not belong to N95 and medical masks, but it can still play a protective role against droplets for the general population. However, for patients who have developed symptoms, it is recommended not to use a mask with a breathing valve, because the airflow is unidirectional, it can not block the droplets with the new coronavirus from spilling out of the inside of the mask, which may lead to infection to others.