London: Cooling temperatures raise the risk of heart attacks, researchers warn.
About 200 extra heart attacks are linked to each drop of 1 degrees Celsius in outside temperature, a study shows.
The highest risk is within two weeks of a reduction in average daily temperature, with the elderly and heart disease patients most vulnerable.
But temperatures getting hotter cause no extra risk, according to research published by British Medical Journal online.
Researcher Krishnan Bhaskaran, of the London School of Hygiene and Tropical Medicine, said there was a 2 per cent increase in the risk of heart attack in the next 28 days for each 1C fall in temperature.
"This translates to around 200 extra heart attacks, so if there are successive falls over a number of days there would be additional sets of extra heart attacks," he said.
Researchers analysed data on 84,000 hospital admissions for heart attack between 2003 and 2006 in England and Wales, and daily temperatures from 15 geographical areas.
People who had been taking aspirin long-term are less at risk, they found.
Previous research suggests exposure to the cold increases blood pressure.
The researchers said the lack of increased risk as weather gets warmer is possibly because Britain rarely gets very hot in global terms. But Dr Tim Chico, from the Cardiovascular Biomedical Research Unit at the University of Sheffield, said: "This study used complex maths which can overestimate risk or not take other important factors into consideration."
