During the epidemic, most of the masks used in general are with or without valves, and the masks with valves have a stronger dust control effect. Therefore, it is not recommended to use masks with valves during epidemics, because the valve is the breathing door after getting out of the dusty environment, and you can breathe smoothly after opening it. But sometimes there is a risk when such valves fail. If it is opened frequently, this large particulate matter gets stuck, which affects its protective effect against viruses. Medical masks use non-woven fabrics and electrostatics that are adsorbent to viruses, so try not to use valved masks during an epidemic. Valved masks should be used in the process of real-time inspection of its sensitivity, to prevent the mask broken or contaminated, and timely cleaning masks. Don’t touch the inside of the mask, so as not to bring the virus to the inside of the mask, resulting in inhalation of the virus into the oral mucosa or nasal mucosa. Source: Dr. Yurai