Wu Zunyou, the chief epidemiologist of the Chinese Center for Disease Control and Prevention, answered the question "When do I need to wear a mask and when do I need to wear a mask", saying that it is getting hotter and everyone is wearing a mask. I have been paying close attention to it, and with some student cases, everyone pays more attention to this issue. In principle, there is no need to wear a mask in a well-ventilated place, as long as the ventilation is good, it should be safe.

Wu Zunyou said, let's talk about the situation where masks are not needed. Outdoor spacious places, such as playgrounds, parks and streets with few people, do not need to wear a mask; in addition, there is no need to wear a mask at home. Working in low-risk areas does not require wearing masks in offices, construction sites and factories. There is no need to wear a mask when exercising outdoors. Primary and secondary schools that people are particularly concerned about in low-risk areas do not need to wear masks. This is a principle for those who do not often go to other unfamiliar places, live in relatively fixed environments and are in low-risk areas. In this case, basically no mask is needed.

For places that need to pay special attention to wearing masks, Wu Zunyou said that in places with poor air circulation and airtight, closed means of transportation, such as airplanes, high-speed rails, subways, and buses, should be used. Then there are closed public places, such as places where people take elevators, with poor ventilation. Special attention should also be paid to hospitals. When you go to the hospital or accompany your relatives and friends to the doctor, you must wear a mask in the hospital environment. There are also public service windows, such as cash registers in supermarkets wearing masks and bank counters. Don't be too entangled in the question of wearing a mask. One of the main principles to master is that the risk of ventilation is small. As I mentioned earlier, special attention should be paid to enclosed places, and other places should be determined according to the situation.