There is a risk of virus transmission through centralized air conditioning, which carries the risk of transmitting a variety of viruses, especially those transmitted through the respiratory tract, for example, it may cause the spread of novel coronavirus pneumonia. Ordinary air-conditioning circulation is limited to a particular individual environment and does not normally cause transmission in other rooms. The air flow of a central air-conditioner has a wider range. If there is a patient with neo-coronavirus pneumonia in a certain ward, the air flow through the central air-conditioner can carry the virus to other rooms and cause infection of patients in other rooms. Therefore, in the event of an epidemic, it is not recommended to turn on the central air-conditioning, and ordinary air-conditioning can be chosen. Of course, the possibility of spreading the virus through central air-conditioning is not very great because the concentration of the virus will be very small under the circulation of central air-conditioning and the possibility of infecting people will also be very small.