Appropriate evaluation of allergen-tight encasings

Covering mattresses with allergen-tight encasings is a well-established mea sure for reducing house dust mites and their allergens which leads to a cli nical improvement. Patients often fear a sleeping discomfort, especially re lated to sweating and heat resistance. In order to measure the passage of h eat and humidity in different allergen-tight encasings the non-profit makin g Swiss Federal Laboratories for Materials Testing and Research (EMPA), Swi tzerland, developed a device called the sweating torso. This sweating torso is a human torso-seized system able to radiate heat and to transpire water . We put the sweating torso in a bed in between a mattress and a blanket bo th covered by an encasing. We then tested 9 different encasings for their a bility to pass humidity and heat by measuring temperature and weight gain f rom condensed water for 8 hours. We compared the results with those obtaine d using a mattress and blanket without encasing or with an encasing with a known high water vapour resistance as a positive control. During the experi ments the temperature inside the sleeping cavity and outside the bed showed only a slight increase of 1 degrees C or less for all 9 tested encasings w hile the control encasing showed an increase of 2.6 degrees C. In addition, the bed showed continuous weight gain from condensed water of about 85 to 177 g and a fast drying behaviour, while the control encasing shows a highe r increase of 210 g condensed water and a considerably worse drying behavio ur. In conclusion, all 9 tested encasings showed a good water vapour and he at permeability. Our results do not indicate any evidence of increased swea ting by using the bed encasings.