Summary 

Human exposure to high temperatures over short and long periods can have serious implications for health, productivity and infrastructure. Many of these impacts are already being felt in places around the world, including in South Africa. For example, in Gauteng, Pretoria has about an average of 10 days per year which can contribute to a heat wave (maximum temperature 35 °C or higher) while for Johannesburg it is about four days per year (maximum temperature 32 °C or higher) (SAWS, 2021). Given the current context of global warming, the number of hot days are likely to increase, hence the need for a Heat Action Plan and early warning system for the province of Gauteng.  

Here, we assessed the impact of heat on mortality in Gauteng province to identify thresholds at which potential warnings could be issued to reduce the risk of heat-related deaths. We found that maximum temperature had the strongest associations with mortality therefore we recommend this metric for use in an early warning system. Our results showed that children younger than 5 years and older adults (>65 years) are at greatest risk of mortality as maximum temperature increases beyond 30oC. Lower temperature thresholds (31 °C and 32 °C) resulted in more deaths because they occurred more frequently and affected people more often.

View the complete Policy Brief: Heat and health impacts in Gauteng, South Africa – Towards an Early Warning System