UK warns hot weather raises cardiac arrest risk for active adults

An amber heat-health alert covered all of England from 9pm on Friday 26 June until 9am on Sunday 28 June, as officials warned that extreme heat can raise the risk of cardiac arrest, heart attack and stroke in people who think they are fit enough to push through outdoor exercise.

The UK Health Security Agency says runners, cyclists and walkers are among the groups most vulnerable in hot weather because prolonged physical activity outdoors adds to the strain on the body. NHS guidance says people should avoid strenuous exercise in the hottest part of the day, typically 11am to 3pm, and limit alcohol because it can worsen dehydration.

The warning lands against a clear rise in heat-linked deaths. UKHSA’s latest heat mortality monitoring report for England recorded 1,311 heat-associated deaths during the four heat episodes of summer 2024, 282 more than predicted from temperatures and the historic temperature-mortality relationship. The highest heat-associated mortality rates were among people aged 85 and over and those aged 75 to 84.

The 2024 report is the first to be published as official statistics, and for the first time it breaks deaths down by place of death, cause of death and Local Resilience Forum area. UKHSA says that level of detail is meant to sharpen local preparedness as heat events become more frequent and intense.

The recent figures sit on top of a troubling run of hot summers. UKHSA estimated 2,295 heat-associated deaths across five heat periods in summer 2023. An Office for National Statistics and UKHSA analysis of the 2022 heat periods found 3,271 deaths above the five-year average in England and Wales, including an estimated 2,803 excess deaths among people aged 65 and over in England.

UKHSA heat-health alerts are designed as early warnings for the health and social care sector, responders, voluntary groups and government when high temperatures are likely to affect health. The current amber alert for all of England shows the system is active again, and it reinforces a message that public-health officials have been pressing for years: hot weather can hit younger, active adults hard, especially when exertion, dehydration and alcohol combine.