Regional and seasonal variability in human thermal stress in Poland

Abstract

The study objective was to determine the spatial and temporal variability of Poland’s bioclimatic conditions and to designate heat-stress regions with the Universal Thermal Climate Index (UTCI) application. The study was based on daily data from the multiannual period 1966–2021 obtained for 37 stations in Poland, provided from the resources of the Institute of Meteorology and Water Management–National Research Institute (IMGW-PIB). The aforementioned data provided the basis for the calculation of the Universal Thermal Climate Index (UTCI). The study revealed high variability of bioclimatic conditions in Poland, both in temporal and spatial terms. Bioclimatic regions characterised by the different occurrence of heat stress were distinguished and characterised. Regions in the south-west and west of Poland proved the most favourable in bioclimatic terms, with the highest number of days with no thermal stress. In these regions, the highest UTCI values were observed, while the lowest were recorded in the northeast of Poland and at the east coast of the Baltic Sea. Among unfavourable biometeorological conditions, the ones causing hypothermia have so far occurred more frequently than the ones causing overheating of the human organism. However, UTCI has increased during the study period; therefore, under proceeding global warming, an increase in the frequency of occurrence of heat stress can be expected. So far, the most intensive increase in UTCI values in Poland was recorded in spring and the weakest in winter.