Water when becomes vapor is invisible and enters the air; this reduces the temperature of surrounding and cools the body. Absolute humidity, which is the amount of vapor present in air makes changes in the temperature and the pressure can be measured using a device called psychrometer or hydrometer.
When buildings were constructed traditionally, the insulation in them were weak which allowed the moisture to flow in and out of the buildings, but the new 20th century buildings have sealed the moisture movement resulting in the problems like mold and mildew development.
To remove excess moisture in the air, a process called dehumidification has to be carried out which is generally done by using dehumidifier. When this excess humidity is left unresolved, it leads to health issues and causes damage of things like bags, belts, shoes etc.
Humidity tends to vary from place to place; the recommended level of humidity for human is between 30 to 60%. However, humidity when becomes more or less than the recommended level, will have adverse effects on health such as irritation to skin, thirstiness, general discomfort, anxiety, respiratory problems and so on. Hence humidity should be controlled to avoid all these problems, and when steps are taken at earlier stage the expenses will also be lesser comparatively.