GE-I-2: Heat-related mortalities | Umweltbundesamt

GE-I-2: Heat-related mortalities

In years with an above-average number of hot days, there are more mortalities than expected in the absence of heatwaves. In 2003 an additional 7,500 individuals died, while for 2006 and 2015 research indicates approximately 6,000 additional mortalities.

Heatwaves cause additional mortalities

Since the beginning of the current millennium, there has been a succession of intensive heatwaves in Germany and most other European countries. Between 2000 and 2018 eight of eleven hottest years were observed since weather records began in 1881. An exceptionally high number of hot days was recorded in 2003, 2006, 2010, 2013, 2015 and 2018. In 2018 there were on average more than 20 hot days in Germany; this is the greatest number of hot days recorded since 1881. In 2003 there were on average 19 hot days and in 2015, on average 17 hot days were recorded nationwide. 

Heat exposure causes the body to lose more fluid than under normal conditions. This fluid loss can lead to dehydration (lack of water in the body) and may also entail diminished viscosity of the blood. These phenomena increase the risk of thromboses and other cardio-vascular conditions. When thermoregulation (the mechanism of the human body which maintains a constant body temperature of approx. 37°C) is restricted, this can bring about disorders in the human water and electrolyte balance which may result in life-threatening impairments of the cardio-vascular system. In particular older and frail people are very vulnerable to heat stress; this also applies to patients with chronic diseases such as cardio-vascular or respiratory conditions³. Furthermore, environmental conditions have a bearing on health risks. As demonstrated by studies, in built-up urban areas⁴, where so-called urban heat islands develop and where increased ozone and fine particulate values occur⁵ health risks are increased.

In mortality statistics, mortalities related to heat effects are typically attributed to other causes of death (e.g. conditions of the cardio-vascular system). If the amount of mortalities exceeds the seasonally typical and thus expected values, this is taken as an indication that there are extraordinary events involved. In determining the indicator ‚heat-related mortalities, aggregated mortality data from the Statistische Bundesamt (StBA/Federal Statistical Office) were used which describe the weekly total mortality per Federal State and per age cohort for the period from 2001 to 2015.

The mathematical model employed describes the non-linear link between high temperatures and mortality rate. Within a range of between 10°C and 20°C of a weekly mean temperature, mortality is relatively constant, whereas at a weekly mean temperature of more than 20°C, it rises distinctly. This increase is particularly pronounced in age cohorts of 65–74, 75–84 and 85+. The weekly mean temperature indicates the mean value of all hourly values within a week while taking special note of day and night temperatures. Weeks with mean temperatures exceeding 20°C typically also contain one or more hot days. 

The number of heat-related mortalities is estimated as the difference between the modelled mortality and a hypothetical mortality regime which would prevail where weekly mean temperatures did not exceed 20°C. 

The precise method of estimation is described in a special issue of the Bundesgesundheitsblatt entitled ‘Gesundheitliche Herausforderungen des Klimawandels’ (particular challenges involved in climate change)⁶. The outcomes show that in 2003 the number of people who died was higher by 7,500 mortalities than would have been expected in the absence of a heatwave. For the years 2006 and 2015 respectively, approx. 6,000 additional mortalities were recorded. 

These mortalities occur especially in age cohorts 75–84 and 85+, while the rate per 100,000 inhabitants is particularly high in cohort 85+. In the period between 2001 and 2015, weekly mean temperatures exceeding 20°C occurred less frequently in the north of Germany, which means that most of the heat-related mortalities occurred in the centre or the south of Germany

^{3  Kovats R. S. & Hajat S. 2008: Heat stress and public health: a critical review. Annu. Rev. Public Health 29: 41-55.
4  Gabriel, K. M. & Endlicher W. R. 2011: Urban and rural mortality rates during heat waves in Berlin and Brandenburg, Germany. Environmental pollution 159(8–9): 2044–2050.
5  Eis D., Helm D., Laußmann D., Stark K. 2010: Klimawandel und Gesundheit – Ein Sachstandsbericht. Berlin, 244 S.
www.rki.de/DE/Content/Gesund/Umwelteinfluesse/Klimawandel/Klimawandel-Gesundheit-Sachstandsbericht.pdf
6  an der Heiden M., Muthers S., Niemann H., Buchholz U., Grabenhenrich L., Matzarakis A. 2019: Schätzung hitzebedingter Todesfälle in Deutschland zwischen 2001 und 2015. Bundesgesundheitsblatt – Gesundheitsforschung – Gesundheitsschutz. Volume 62, Issue 5: 571–579.
https://doi.org/10.1007/s00103-019-02932-y}

Interfaces

GE-I-1:Heat exposure

GE-R-1: Heat warning service

Objectives

Right to life and physical integrity (German Constitution, Art. 2).