Climate and Work Load Both Interact with Individual Characteristics inDetermining the Human Heat Stress Response (Klimaat en Werkbelasting Beinvloeden Beide de Individuele Karakteristieken bij het Bepalen van de Menselijke Reactie op Hittebelasting)

摘要

Heat exposure data from comparable heterogeneous subject groups (Large variationsin VO(2max), mass, body surface area (A%), fat content, A(du)/mass ratio) who worked on a cycle ergometer at a Load relative to their V0(2max) (RL) in a cool (CO; 2l deg C, 50%rh), warm humid (WH; 35 deg C, 80%) and a hot dry (HD; 45 deg C, 20%) environment (n=24) or who worked at a fixed toad (FL; 60W) in a WH (n=27) and a HD (n=30) climate, were analysed for the interaction of individual characteristics with climate type and work load. Exposures lasted 75 to 90 minutes for different conditions (constant within each condition). The observed results can be explained by a model, in which heat production and heat dissipation capacities are correlated with the subjects VO(2max), the internal heat liberation is based on metabolic rate, heat loss capacity is determined by the climate, body mass acts as a heat sink and skin fat layers only exert an insulative effect at low blood perfusion rates. This study showed, that effects of individual characteristics on human heat stress response cannot be interpreted without taking into consideration the heat transfer properties of the climate used and the metabolic heat load resulting from the type of workload.