A new study from University College London (UCL) claims that while air pollution in various guises might be responsible for part of the rising death toll associated with heat waves, a simple failure to keep cool is far more likely to be the problem.

The study, published online in the journal Environmental Research, looked at daily death rates for London’s over 65s between 1991 and 2002 to see what links could be made between mortality, the weather and other environmental factors.

The model included daily temperatures, humidity, sunshine and wind and assessed any effects of atmospheric ozone, particulates and sulphur dioxide.

The team found that when temperatures topped 18&;degreeC, mortality rates in the vulnerable 65+ age group rose progressively as the days grew hotter.

They also found there were more deaths on hot days early in the summer, before people had a chance to acclimatise to the heat.

While high levels of ozone, particulates and sulphur dioxide did play a role in mortality rates, it was less significant than previously thought, claimed the study.

This is because other anaylses have failed to take into account people’s ability to adjust to heat by late summer, wind that might stop pollutants collecting and varying levels of direct sunshine.

Professor Bill Keatinge, of the Royal Free and University College Medical School, said: “Ozone, particulates and sulphur dioxide have been fingered as the culprits when hot weather is more likely to have caused the deaths.

“On hot days, older people are more likely to be dying from heat stress than from air pollution.

“The basic message of ‘keep cool when the weather is hot’ seems to be being drowned out by exaggerated concern over air pollution. Runs of hot days are particularly dangerous.

“The fact that deaths were higher in early summer rather than late summer suggests that some people were unprepared for the hot weather and may not have taken the necessary precautions to keep cool.

“The heat wave in France in 2003 which killed 14,000 people was an unfortunate example of what happens when people are not prepared for hot weather.

“Even Britain, which has around 800 heat-related deaths in an average summer, had more than 3,000 in the exceptionally hot summer of 2003.”

While he believes pollution’s direct role in summer deaths has been exaggerated, Dr Keatinge warned that wider environmental issues were potentially playing a part.

“Global warming may well produce runs of hotter days than have ever been experienced here before,” he said.

“And we need to be prepared for that happening in the UK with little warning.”

By Sam Bond

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