In a summer when the highest temperature so far has been only 28C (82F), it seems perverse to mention the problems of heat in Britain. But this tepid, wishy-washy summer has left us susceptible to the dangers of heat waves because we rarely acclimatise to really high temperatures.

Heat illnesses are usually linked to extreme climates or marathon runners (Sir Roger Bannister, Letters, July 15). But the work of Professor W. R Keatinge (obituary, May 8) showed how a sudden hot spell in Britain can be lethal. His research revealed that the deadly effects of heat usually appear at the start of a heat wave, when the national death rate can double or triple in the first 48 hours. These deaths result largely from heart attacks, thromboses and strokes, often triggered by a change in blood chemistry, creating blood clots more easily, or by overloading the heart.

These deadly effects were dramatically illustrated during the intense heat wave of August 2003, when the highest temperature record for the UK was broken. More than 2,000 additional deaths were caused by the heat in England, almost a fifth more than usual, and the problem was particularly severe in London.