The control of house dust mites by ventilation: a pilot study.

The house dust mite inhabits bedding and soft furnishings in homes. It is implicated as a major cause of allergic asthma. Maintenance of indoor humidity below a level of 7 g/kg inhibits the growth of the mite population. A pilot survey was carried out by EA Technology in cooperation with the Building Research Establishment to investigate the effect of mechanical ventilation with heat recovery (MVHR) both on indoor humidity and mite abundances. The temperature and humidity in the main bedroom of 11 dwellings were measured over a period of 1 month in February 1992, and dust samples taken from living and bedroom carpets and mattresses. Bedrooms in houses with continuously operating MVHR showed significantly lower humidities and significantly lower levels of mite concentration in dust taken from the bedroom carpet, when compared with similar houses where the MVHR was not continuously operated. The results of the survey support the proposition that the use of MVHR in the British climate can act as an effective means of control of house dust mites. In view of the small sample size, confirmation using a larger sample is desirable.