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The third day of a heatwave is the tipping point … are we ready?

Heatwaves are good news for ice cream sellers, air conditioning manufacturers – and funeral directors. When the sun shines really brightly, people start to die in quite large numbers.

Because heatwaves are comparatively rare in the UK, this phenomenon went unnoticed for many years. The trigger for recent concern was the experience of the city of Paris and its suburbs from August 4-14, 2003. During this period, daytime high temperatures averaged 38.1°C and night-time temperatures averaged 23.3°C. About 15,000 more people died than would usually have been expected.

No one noticed these deaths for several days. When hospital emergency departments began to complain about the pressure on August 8-9, their concern was dismissed as a protest against budget cuts. The first media reports were similarly disparaged by the government.

The minister for health appeared on TV on August 11 from his holiday retreat in the south of France to reassure everyone. The full scale of the emergency only became clear later on the same day, when it emerged that bodies were accumulating faster than the funeral industry could dispose of them. By the time the prime minister returned to Paris to deal with a health crisis that had become a political crisis, the weather had broken.

Around 15,000 people died in the 2003 Paris heatwave. Ekaterina Pokrovsky/Shutterstock

The same weather system affected London and southeast England. At the time, there was no obvious surge in the number of deaths. Later, however, the French experience prompted an investigation by the Office for National Statistics. They estimated that the heatwave had led to 1,500 to 2,000 extra deaths. These had not been identified at the time because of cultural and institutional differences between England and France.

The English system for dealing with the dead is geared to high winter death rates and a preference for cremation. It has spare capacity in the summer. In August 2003, England never ran out of space to store bodies because the crematoria were able to absorb the increase. In Paris, refrigerated trucks had to be brought in to deal with an overflow from hospital mortuaries. The French preference for burial meant that it was harder to move bodies through the system more quickly.

Since 2003, researchers have examined the pattern of deaths in more detail to try to understand the physiological processes involved and to identify risk factors that could inform national emergency planners. It seems that the people who die in heatwaves are mostly not already at the point of death. Heatwaves did not kill people who would have died anyway within a few days or weeks.

The impact was visible in death rates for 2004 in France, suggesting that lives had been cut short by significant amounts. Night-time temperatures appear to be more significant than those in the daytime. People can tolerate heat during the day provided that they can get sufficient respite at night. The tipping point seems to be three successive nights when the ambient temperature is above 20°C. In France, this has led, for example, to significant investments in air conditioning for hospitals and care homes.

Insufficient plans

Each nation of the UK has its own emergency plan for heatwaves, although England is probably at the greatest risk. The English plan was last revised in 2015 and looks to Local Resilience Forums, which link NHS and local authority public health and social care services with charities and volunteer groups, to plan and lead responses. The Meteorological Office will issue warnings, based on regional weather forecasts. These trigger various levels of media campaign and direct action by local agencies to address groups believed to be vulnerable.

However, it is far from clear that the English system still has the capacity to deal with these emergencies. Close reading of the advice shows that it mostly relies on people acting to protect themselves with little help from any public agency. This assumes that most people will actually see the media campaign and act on it, and that the places where vulnerable people live have systems in place where people will check on them.

Fortunately, the UK weather forecasts suggest that the current weather is likely to be a hot spell rather than a heatwave, and too brief to do much damage. But the weather is entirely consistent with the projections from climate change models that extremes are becoming more likely. Heatwaves at least as intense as early August 2003 will recur and so, no doubt, will the casualties.

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