Occupational needs and evaluation methods for cold protective clothing.

The aim of the study was to evaluate the needs for and properties of the occupational cold protective clothing with different methods and the risks related to work in cold conditions from the point of view of occupational hygiene and clothing physiology. The thermal insulation of textile materials and clothing was investigated with the equipment, methods and parameters developed especially in cold and windy conditions in dynamic and steady states. Also the simulation and calculation of results were done and compared to the measurements. The cold exposure from the point of occupational hygiene was evaluated in working life to evaluate the risk of cooling and frostbite and utility ranges of clothing. The function of the sweating hot plate constructed and cylinder in the wind tunnel could be regarded adequate for the evaluation of winter clothing with good precision, stability and repeatability. The measured total thermal resistance was mainly dependent on, and operative thermal resistance independent of, temperature. The operative thermal resistance was also very sensitive to errors in measurement procedures. The heat flow usually evaluated by thermal and water vapour resistance could be substituted for total thermal resistance. Both the measurements and theories showed that, in addition to air permeability, also the ambient temperature, air gaps, contact layers and thickness of clothing were important parameters. Increase of wind (1...8 m/s) decreased the total thermal resistance and mass transfer up to 60% depending on conditions. The comparison of calculation models with material measurements proved the value of the simulation models. The reason for differences between the methods was mainly due to changes in water vapour resistance in the cold. The heat flux method was exact enough in the evaluation of the insulation of clothing in the field but in sweating conditions the condensation and evaporation must be taken into consideration. In the case of heat debt in the cold the heat flux method gave smaller values than the thermometric method. The material measurements diverged logically from the clothing measurements but material methods had a better capability to analyze the differences of material ensembles. In the evaluation of body cooling and performance degradation in outdoor work the physiological recommendations given were temporarily exceeded in 70% of the cases measured (N = 143). The cold problems already occurred in temperatures from 0 to 10 degrees C. The reasons for the cold problems were related to the type of work e.g. wind to the face and long exposure to the feet caused frostbite.(ABSTRACT TRUNCATED AT 400 WORDS)