Opening windows helps reduce the amount of viruses that may be present indoors and helps renew the air inside. The air outside is “diluted” and it is almost impossible to bring the virus indoors. The correct way to open windows is as follows: 1. Ensure the number of ventilation: at least 3 times a day, while the ventilation requirement for potentially contaminated workplaces is about once every 5 minutes. 2, choose a good ventilation time: 8:00-11:00 in the morning and 13:00-16:00 in the afternoon is the best ventilation time, those who live by the road, pay attention to avoid the morning and evening rush to open the window, while opening the window ventilation pay attention to keep warm. 3, pay attention to the length of ventilation: in the absence of wind or breeze, it is recommended to open the window for 20-30 minutes. If you only open a small slit, it is recommended to open the window for 30-60 minutes.