Itwasautumn.The ginkgoleaveson the campuswereturningyellow.Withthe background of blue sky and white clouds, they felldownlike a butterfly dancing in the air.Thetrace ofheatand humidleft by thesummer was disappearingand the weather was getting cold. Itwasgetting dry.David'sdad boughta new humidifier, inwhichessential oils of different favors could be used.WhenDavidcame home, he put away his schoolbag first and put on slippers.Then,heopened the humidifier. As thefragrantmistblew on his face in a comfortable way, he felt relaxedandpleasant.
At the weekend,Davidsuddenly felt thathisthroatdidn't feel well, andhecoughednow and then. Hismomwas worried about him andasked,"It's autumn now.Do you catch cold when you went running in PE lesson?"Heshook his head andreplied,"I don't think so.The PE lesson was delayed until next week because of a mathquiz this week."After thinking for a while, his dad said,"I saw a report a few days ago. I'm thinking if the humidifier is to blame."Davidasked confusingly,"Does the humidifier make people sick?"
Momcontinuedimmediately,"You have reminded me! Inoticed a healthtip.Ifahumidifieris usedfor a long time without cleaning andsterilization,itsinner wall will breedbacteria. Ifthere arepathogenic bacteria, they will enterintorespiratory tract and lungs through the tiny droplets sprayed from the humidifier. These water droplets with pathogenic bacteria may cause allergic pneumonia."
Davidaskedcuriously, "Butthe air is not 100% clean.Why usinghumidifiermakespeople ill?"
His dad explained patiently,"Sinceyou talked about the air, let's start withitshumidity. Generally speaking, a humidity of 40% to 70%is suitable forhuman body.When the humidityin the air remains at45% to 65%,it's hard forthegermstospread. Autumn has arrived,the air is dry.Dry lips begin to peel. When the humidity is lower than 30%,we should turn on thehumidifier. However, when the humidity is over 80%, it is easy to breed bacteria, dust mites and molds.Youwill feel sultry, and there will be condensation on the wall, the floor and the table. At this time,we should turn offthe humidifier andopenthe windowto ventilate,or what we just said will happen."
Mom added,"So,we should put thehumidifieraway, andnot let it blow on our face.Ifthe droplets sprayed from the humidifier have germs,they willenter respiratory tracteasily.In a general way,we should shut it down when it was turned on for two hours."
Thenmomturned to dad and said,"Generally speaking, it is not recommended to add other thingsinthe humidifier.These chemicals may irritate lungs.Andwaterinthe humidifier shouldbechangedevery day. It should be cleaned onaweekly basis."
Author: Lu An
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