Atmospheric heat exchange of the human being, bioclimate assessments, mortality and thermal stress.

In epidemiological investigations of the impact of the atmospheric environment on mortality usually only air temperature, in addition to sometimes relative humidity, are used, although it is generally known that the heat exchange conditions of the human body also depend on water vapour pressure, wind velocity, and short- and long-wave radiation. The state-of-the-art approach to this problem is the application of complete heat budget models which allow thermophysiologically significant assessments of the above-mentioned meteorological variables taking metabolic rate and isolation of clothing into account. The application of such a model to 30-year mortality data of Baden-Württemberg (SW-Germany) shows, in winter, increasing daily mortality rate with decreasing "perceived temperature." (a term which relates temperature to a fixed standard condition). A sudden warming during a cold period also results in an increase in mortality, a certain contradiction which has not yet been able to be explained. During cold spells a marked increase in mortality with a delay of 3 days can be observed. Above normal values last for about 4 weeks and will then be partially compensated by an "undershot". Generally the explanation of variance in winter is distinctly lower than in summer, probably because in winter there is rarely direct exposure to outdoor conditions. The degree of cold stress is likely to serve only as an indicator for indoor conditions which promote infectious diseases.