Heatwaves and mortality rates in Northern Senegal: temperature-related morbidity and mortality and associated risk factors

Summary

The Sahelian zone of Senegal experiences heatwave events, remarkably in 2013 exceeding 45°C with an associated morbidity and mortality rise. This study documents recurrent extreme temperatures in this part of the country, and highlights associated increases in health consultations, self-reported morbidity and documented mortality, and risk factors for exposure.

Background

The existing scholarly literature confirms heat wave events over America and Europe that impact human health in terms of excess of mortality and morbidity. The comparable health impact of heat waves in Africa is still poorly understood due to a lack of scientific study. Yet in the northern part of Senegal, on the Sahelian belt, high rates of extreme temperatures are documented. This study utilised data on climate, health, socio-economic, environmental and cultural characteristics, and vulnerability factors such as the practices and behaviours of populations to document the effects of the extreme temperature recurrence on community health and mortality in this part of the country.

Description of study

This was a transdisciplinary study, using multi-sectoral collaboration to reveal actionable adaptation strategies to heat waves. Fields of expertise required for the study included climatology, geography, ecology, epidemiology, public health, statistics, sociology and geomatics.

The resilience of health systems and communities to the impacts of climate change is dependent on the adoption of adaptation measures based on scientific evidence, but climate scientists often do not have the required resources to analyse climate-related health risks which are necessary to design climate services that are responsive to the needs of the health system in an environment of temperature rise..

This study was implemented in the Northern and Northeastern part of Senegal, and covers the departments of Dagana, Podor, Louga, Linguere, Matam, Ranérou, Kanel and Bakel, located in the regions of Saint-Louis, Louga, Matam and Tambacounda. To do this, climate data (temperatures) and health data (morbidity, mortality) were collected for April, May and June from 2009 to 2019. These data were complemented by surveys of exposure risk factors of 1246 households. Univariate and bivariate statistical analysis was applied, and cartographic techniques provided visualization of the major climatic and health indicators.

Outcomes

An increase in temperatures compared to seasonal normal for the 1971-2000 reference period was confirmed, with thresholds exceeding the 90th percentiles (42°C maxima and 27°C minima), with the highest temperatures during the months of May and June. There was a documented increase in consultations at health facilities, as well as a rise in self-reported morbidity by households, especially in Kanel (17.7%), Ranérou (16.1%), Matam (13.7%) and Bakel (13.7%). The heatwaves of May 2013 were also associated with death, with a mortality rate (observed by medical staff) of 12.4% that varied significantly across departments: Matam (25.2%), Bakel (23.5%), Podor (8.4%) and Kanel (0.8%). Moreover, women suffered greater rates of death (57% of total) than men (43%). Health risks are associated with factors including age (with those over 61 years and under 20 years most at risk), access to drinkable water (households with running water in the home are less exposed to the effects of increasing temperature than those who get water from standpipes (91%) or wells (86%), type of fuel (people living in households using wood (85%) or charcoal (85%) are more affected than those using butane gas), type of housing and construction materials (people living in  or straw huts are less exposed to the temperature effects than those living in low-rise (76%) or multi-storey (80%) houses), etc.

Lessons

This study demonstrates the vulnerability of populations in these localities is not just related to the occurrence of extreme temperatures, but also to other factors, such as adaptation strategies or the responses of communities to the health impact of heat waves. Thus, the prevention of health problems related to rising temperatures requires the development of an early warning system for heat waves in order to strengthen the resilience of populations and the health system to the impacts of climate change.

Impact

This research had a significant impact because it contributed to a better understanding of extreme climatic phenomena such as heat waves, their impacts on the mortality of populations in Northeastern Senegal and environmental and social vulnerability factors. Faced with the threats of the impacts of climate change on the survival of populations in the North, this research has provided scientific evidence that can be used to develop adaptation measures to strengthen the resilience of the health system and communities. These data can also serve to empower climatologists to analyse climate-related health risks to guide strategies that mitigate the effects of heat waves for specific stakeholders. The multisectoral framework used in this study serves as a model for generation of quality scientific information to strengthen the capacity of critical actors (climate scientists, health system providers and communities) to mitigate the health impacts of heat waves on population health in the Sahel.

About Ibrahima SY

Dr Ibrahima SY is a Senior Lecturer in the Department of Geography at the University Cheikh Anta Diop (UCAD), Dakar, Senegal. He is a grantee of Climate Research for Development in Africa (CR4D), funded by the UK Foreign, Commonwealth & Development Office (FCDO, formerly DFID), the Weather and Climate Information Services for Africa (WISER) programme and the Africa Climate Policy Centre (ACPC) of the United Nations Economic Commission for Africa (UNECA) under the auspices of the African Academy of Sciences.