Identification of local heat thresholds and related health impacts: Nairobi, Mombasa, Kisumu Cities in Kenya
This research is carried out by Joyce Kimutai 1,2, Patricia Nying’uro1, Luke Harrington3, Wesley Oghera4, Friederike Otto5 with funding support from the Global Disaster Preparedness Center.
As the climate warms, more days with extremely hot temperatures are occurring across the world. With thousands of excess deaths every year, the health effects of hot weather are fast becoming a global public health challenge for the 21st century. Studies on the relationship between high temperatures and hospital visits, admissions and mortalities especially in vulnerable parts of the globe e.g. Sub Saharan African cities are however largely absent. In this study, we define local heat thresholds for three Kenyan cities (Nairobi, Kisumu and Mombasa) and use these thresholds to evaluate the heat-health impacts of the most recent heatwaves. We utilize daily maximum and minimum temperature data from Kenya Meteorological Department for two stations in each city and monthly health data (visits, admissions and mortalities) from two public health facilities in close proximity to the weather stations.
Our results show positive associations between high temperatures and hospital admissions across the three cities. The correlations are statistically significant albeit very low. While the correlations found do not suggest a common relationship, they should not be interpreted as evidence of no relationships as it does only mean that they cannot be detected in the data available to us. We also see indications of a delayed effect of heat on mortalities albeit not in all cases. We use this analysis to propose heatwave definitions for issuing health alert warnings in each city: daily maximum temperature of 32+ for 3 or more days in Nairobi, daily maximum of 37+ for 3 or more days in Kisumu and a daily max of 36+ for 3 or more days in Mombasa. These thresholds can be used to trigger protocols e.g., the deployment of heat-health action and emergency response plans or mitigate against the effects of extreme heat in the three Kenya’s economic hubs. We draw attention to hospital managers and medical practitioners to pay particular attention to patients during such high-temperature periods. There is need for additional research on the relative risks associated with chronic exposure to high temperatures (i.e. thresholds which are exceeded for weeks at a time) versus punctuated spells of several days where those same thresholds are only exceeded by another two or three degrees. There is also scope for further work to investigate the potential exposure-lag response association between temperature and in-hospital mortality.
1 Kenya Meteorological Department, Kenya
2 African Climate & Development Institute, University of Cape Town, South Africa
3 School of Science, Division of Health, Engineering, Computing and Science, University of Waikato, New Zealand
4 Ministry of Health, Kenya
5 Grantham Institute, Imperial College London, UK