THERMOPHYSIOLOGICAL RESPONSE OF HUMAN BEINGS WORKING IN COLD THERMAL ENVIRONMENTS

Summary: In this work, the simulation of heat and mass transfer from an individual working in cold thermal environments such as those frequently occurring in the Portuguese cold industrial activities is presented. Three different typical cold conditions were selected corresponding to freezing chambers, refrigerating cold stores and cool controlled air temperature manufacturing workplaces. To obtain the present results a numerical procedure based on a modified version of the Stolwijk thermoregulation model was used. Taking into account the temporal evolution of skin, rectal, lungs and hypothalamus temperatures, a study was presented where it is analyzed the thermophysiological difference between a human being working indoors in three cold spaces. For each kind of cold space two or three different situations were selected: (i) the real situation, with the individual wearing inappropriate clothing insulation, associated to longer exposition times and shorter recovering periods than the recommended values; (ii) one ideal scenario, with the human being wearing proper clothing for the real exposure and recover times; (iii) another ideal case, with the worker following the times of exposure and of recover recommend for the real clothing insulation that he wears. The results clearly show that, for the low temperatures characteristic of the freezing chambers associated with deficient clothing insulation, prolonged exposures and insufficient recovering periods, the physiological strain of human beings working on those conditions is amplified when compared to the ideal situations above described. For the other two cases, refrigerating cold stores and manufacturing workplaces, the most frequent scenario is characterized by the use of ensembles with an insulation value greater than the recommended. In short, deep changes in the protection clothing used are required, particularly when a long time is needed to complete the work tasks.