Cold Stress and Human Mortality: A Case Study during the January 2017 Cold Spell in Eastern-Southern Europe

Low temperatures pose significant health risks, particularly for the elderly, infants, and individuals with fragile health, especially those with respiratory or cardiovascular conditions. Moreover, social factors such as inadequate housing, limited access to heating, and insufficient healthcare further exacerbate vulnerability. An extreme cold weather event affected Eastern and Southern Europe in January 2017, with temperatures remaining well below long-term averages for several consecutive days. Several countries recorded their lowest temperatures in decades in certain regions. Among them, Poland, Albania, Bulgaria, the Czech Republic, Italy, and Greece reported several deaths associated with the cold, many of which involved migrants or homeless individuals. This study investigates the relationship between decreased temperatures and excess mortality in eight countries - namely Poland, Romania, the Czech Republic, Italy, Albania, Serbia, Bulgaria, and Greece - during the prolonged cold spell of January 2017. Using daily temperature data and weekly all-cause mortality records for the entire population of these countries, the analysis identifies a marked increase in mortality coinciding with periods of extreme cold. The period covering 2015, 2016, 2018, 2019, and 2020 was used as a reference to estimate the average mortality rates for January in each country. Increases in mortality rates during January 2017 ranged from approximately 20% to over 40% on a monthly basis. Focusing on a weekly basis, during the second week of January 2017, when the cold spell intensified, the highest excess mortality rates were observed, reaching 25% in Romania and the Czech Republic, and up to 55% in Serbia. We further analyzed daily mortality rates using Thessaloniki, Greece, as a representative case study to investigate changes in mortality caused by cardiovascular diseases during the cold spell. The analysis investigated anomalies in minimum temperatures and their association with age-stratified mortality rates, categorized by 5-year age groups. In January 2017, the city recorded the highest number of such deaths compared to any other January in the 2013–2018 period. Among all age categories analyzed, the elderly were found to be the most vulnerable to the impacts of extreme cold. The population aged 80 and above was particularly impacted, with mortality in this group increasing by 27% relative to the corresponding monthly average. These findings underscore the critical need for regionally tailored public health strategies and early-warning systems to protect at-risk populations during cold spells. As climate variability increases, even traditionally milder southern European regions may face more frequent or intense cold-related health risks.