A solution, based on low-cost solar-powered air drying, to heat stress in buildings located in developing countries with a hot and humid climate is presented. The air-drying facilities are described and a validation of the ensuing benefits through comprehensive human exposure studies is given. A prototype of a solar powered supply system for dried air was constructed and supply air was led to six personal units for ventilation and cooling placed in cubicles simulating office workplaces. 123 heat-acclimatized people were exposed for one hour in each of the cubicles. It is concluded that drying indoor air reduces heat stress among heat-adapted people in hot and humid offices and that the low-cost solar powered air drying system functioned satisfactorily , although some improvements are recommended. The drying power of the sun can be stored in recovered silica gel beads and used for other purposes. It is suggested that further research could explore the possibility of desiccant drying of agricultural products during the rainy season. (ARW) 30 refs.