Ventilation with windows open is recommended during epidemics of new pneumonia infections, but it depends on the outside environment. If the outside environment is favorable, proper ventilation can be carried out. When there is haze, clear pollution, and high winds that cool the air, it is important to be careful of colds or other illnesses when opening windows. Dirty indoor air can affect your health, and may cause the deposition of other pollutants if windows are not opened for a long time. It is recommended to open the windows 2-3 times a day, and after opening the windows to ventilate the room can do some corresponding physical exercise, to avoid the body slack time is too long, caused by the circulation of qi and blood is not smooth and lead to disease. Ventilation can also make the home disinfection of chemical deposits slightly dissipated, disinfectant is too strong can have an impact on the human body. So you can also open the windows after disinfection to reduce the level of harm. Source: Dr. Yurai