Heat-related mortality during hot summers in Polish cities

The aim of this study was to estimate a likely number of additional fatalities in ten largest cities in Poland, recorded during heat waves in particularly hot summer seasons. In the period of 1989-2012, for which data on mortality were available, the most intense, long-lasting, summer heat waves occurred in 1992, 1994, 2006, and 2010. The numbers of fatalities in these years were compared to the numbers of fatalities in reference periods. These calculations were undertaken for days during heat waves and also for a longer interval including next 30days after the end of the last sub-wave. An increase of mortality risk for people over 65years of age and for those affected with cardiovascular diseases was noted. The total number of additional fatalities in ten largest cities in Poland could have exceeded 1070 in 1994. During the hottest days in the analyzed period, in some cities, the number of fatalities was more than three times higher than the mean value for the reference period. The results indicate that the increase of mortality during heat waves is a serious threat in Poland already in the present climate and will be even more severe in a warming climate.