Heat morbidity and mortality in Wales: A literature review of UK and international evidence to guide surveillance

This literature review identifies strong associations between various heat exposures - heatwaves, moderate heat, hot nights (diurnal temperature variation), and cumulative heat, and increased morbidity and mortality. Affected outcomes include cardiovascular, respiratory, renal, liver, and mental health conditions, as well as adverse pregnancy outcomes and direct heat-related illnesses such as heatstroke. Vulnerable groups include older adults, children, socioeconomically deprived populations, and some ethnic minorities. Confounding factors such as air pollution and humidity often amplify heat impacts.

While the global burden of heat-related morbidity and mortality is increasingly recognised, the specific health impacts in Wales remain largely underexplored. The UK Climate Change Risk Assessment 2022 (CCRA3) has identified temperature-related health effects as a growing concern, particularly in relation to the risks of heat-related mortality and the resilience of health and social care systems However, in Wales there is a lack of tailored evidence and surveillance systems for heat morbidity and mortality.