流行性感冒、流行性脑脊髓膜炎、猩红热以及麻疹等呼吸道传染病,在冬春季节很容易发生。这些疾病的病原体,大多寄生在病人鼻、咽部,当病人说话、咳嗽、打喷嚏时,病毒、病菌会随着唾沫星子飞到空气中。健康人吸入了空气中的病毒、病菌,就可能发病。冬春季节寒冷,人们在室外活动减少,多集中在室内,这就增加了传染的机会。人们为了御寒,习惯把门窗关的很严,有的甚至将门窗缝隙糊死。这样,室内的空气难以与外面的空气交换。实验证明,在空气 Influenza, epidemic cerebrospinal meningitis, scarlet fever and measles and other respiratory diseases, is very easy to happen in winter and spring. The pathogens of these diseases are mostly parasitic on the nose and throat of the patient. When the patient speaks, coughs and sneezes, the virus and germs fly into the air with the sputum asteroids. Healthy people inhaled the virus in the air, germs, it is possible disease. Cold in winter and spring, people in outdoor activities to reduce, more concentrated in the room, which increases the chance of infection. People in order to keep warm, the windows and doors are used to customs very strict, and some even stormed the gap between windows and doors. In this way, the indoor air is difficult to exchange with the outside air. Experiments show that in the air