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WEDNESDAY, July 30, 2003 (HealthDayNews) -- Cold weather in London is a bigger killer than hot summer weather in that city. And London's cold is more of a danger to people than the cold in Sofia, the capital of Bulgaria.
That conclusion is from a study that compared the temperature effects of the two capitals. The study appears in the latest issue of the Journal of Epidemiology and Community Health.
The researchers wanted to investigate the effects of temperature on death rates in two different European capitals. They decided to compare London's northerly maritime climate with Sofia's more extreme climate.
They examined the association between temperatures and deaths from all causes in Sofia for the years 1996 to 1999 and in London for the years 1993 to 1996. The researchers also assessed daily air pollution records.
During the time periods under study, nearly 45,000 people died in Sofia while almost 257,000 people died in London. Temperatures ranged from minus 6 degrees to 34 degrees Celsius in London and from 17 degrees to 37 degrees Celsius in Sofia.
The two cities' average winter temperatures were much different while their summer temperatures were similar.
In London, deaths increased by more than 4 percent for every degree below the cutoff point of extreme cold -- just over 5 degrees Celsius. In Sofia, deaths increased 2 percent for every degree below the cutoff point of minus 0.46 degrees Celsius. London had more cold days than Sofia.
The study found the effects of the cold extended over a considerable period in London, peaking after a lag of three days, but still evident after 22 days. The authors suggest that shows the cold temperatures in London harm the general population and that the adverse effects of the cold aren't limited to people who are close to death.
Both cities had similar heat cutoff points of about 21 degrees Celsius. But the effects of heat were greater in Sofia where, for every 1 degree rise above the cutoff point, deaths increased by 3.5 percent, compared with less than 2 percent in London.
More information
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