This also applies to houses with poor indoor ventilation. Activities which increase indoor humidity, such as cooking, showering, drying clothes indoors, and evaporative coolers, also lead to larger housedust mite numbers. Conversely, rooms which are well ventilated and dry will have fewer housedust mites. Beds Most of the problems caused by housedust mites result from colonies of mites which live in beds. Housedust mites are common in beds because the environment is warm and humid and skin scales provide an immediate food source.
Mattresses are the most important source of housedust mite allergens.
This is because we spend a significant amount of time in bed, and when we are asleep our face is close to the source of the allergen which is then easily inhaled. Special mattress covers, called encasings, prevent the mattress allergen from escaping into the bed and into the air. They play an important role in allergen avoidance, especially if the mattress is a few years old. These covers can be uncomfortable in hot weather but they can be covered with an overlay as long as it is washed regularly. In addition, the linen and top bedding needs to be treated regularly to prevent build-up of allergens even when a mattress cover is used.