Air Condition System 空调系统

空调打开的时候，我明显嗅到了霉菌的味道。脑海中突然出现了一个镜头……病毒通过空调系统扩散，似乎是一个不错的桥段。
这又让我想到了医院。
世界上通过空气传播的病毒越来越多了，医院还保持那毫无安全感可言的中央空调吗？

When the air conditioner turns on, a smelling of mildew disturbs me. That remainds me of a scene… a not bad bridge scene showing a lump of virus diffusing by the air condition system.
That reminds me of hospitals also.
As kinds of virus which diffusing by air growing, how can hospitals providing us safty feelings by those central air condition systems?