If humidity of the room becomes less than 40%, viruses float in the room for more than 30 minutes. In winter, air outside is very dry so if you ventilate a room frequently, the humidity of the room becomes less than 40%, causing viruses to float in the room for a long time.
If the humidity is more than 40%, viruses floating in the air fall down to the floor. On the other hand, if you open the window and the humidity becomes less than 40%, viruses on the floor go up into the air again.
So it is better to decrease the number of ventilation in winter.
But in the following cases, it is better to ventilate a room:
- when somebody who has a cold came into the room
- when you are starting recovering from a cold
A11. B on the shelf
To keep the humidity high around your nose and mouth, it is better to place the humidifier at the level of your face. If you place the humidifier on the floor, it is possibly dry at the level of your face.
Other important points about a humidifier are:
- Clean the filter of the humidifier.
- Use tap water which contains chloride which prevents germs from multiplying.