The air is thirsty
Apart from temperature and air purity, the third important factor in the maintenance of an ideal room climate is the moisture content of the air. Whilst the danger of excessive humidity in our latitudes is comparatively low, often, during the winter months when rooms are heated, we experience excessively dry air indoors. The consequences of dry air are severe.
Opening the windows will not help to avoid dry room air during the cold season. Instead, it is necessary actively to add moisture to the air. Because just like people, the air becomes thirsty too. The art lies in giving the air just enough water to drink so that it reaches the ideal moisture content level. If moisture is not added to the air artificially, it will try to quench its thirst by taking the moisture from our skin, mucous membranes, plants, wooden furniture, etc. The moisture content level of the air is measurable using an instrument known as a hygrometer (Hygro = Water). The reading given by a hygrometer is called "relative air humidity".
Medical experts recommend a relative air humidity of between 40 and 60 per cent. At these levels, our senses tell us that the air in the room is ideally humidified. Then it is also ideal for our health, for the animals and plants in the room, for furniture, instruments and much more besides.
