Study: Cold kills 20 times more people than heat

Cold weather is 20 times as deadly as hot weather, and it's not the extreme low or high temperatures that cause the most deaths, according to a study published Wednesday.

The study found the majority of deaths occurred on moderately hot and moderately cold days instead of during extreme temperatures.

"Although the risk of mortality due to extremely cold or hot days is actually higher, they are less frequent," said lead author Antonio Gasparrini of the London School of Hygiene & Tropical Medicine.

The study — published in the British journal The Lancet — analyzed data on more than 74 million deaths in 13 countries between 1985 and 2012. Of those, 5.4 million deaths were related to cold, while 311,000 were related to heat.

Because the study included countries under different socio-economic backgrounds and with varying climates, it was representative of temperature-related deaths worldwide, the study said. The sharp distinction between heat- and cold-related deaths is because low temperatures cause more problems for the body's cardiovascular and respiratory systems, it added.

"Public-health policies focus almost exclusively on minimizing the health consequences of heat waves," Gasparrini said. "Our findings suggest that these measures need to be refocused and extended to take account of a whole range of effects associated with temperature."

This report backs up a U.S. study last year from the National Center for Health Statistics, which found that cold kills more than twice as many Americans as heat.

However, both studies contradict data from the National Weather Service, which found hot weather to be the biggest killer, followed by tornadoes, hurricanes and floods. According to the service, cold is only the eighth-leading cause of death.

The discrepancy is likely because the weather service data is not as thorough and focuses more on the weather than the number of deaths caused by it.

"The NWS' fatality and injury information is derived from a database where the primary function is to collect weather reports and any details associated with an event's impact," Brent MacAloney, NWS Storm Data Program Manager said last year. "The fatality and injury information is only supplementary."

The most recent study doesn't project what its findings could mean for the future, particularly with climate change warming much of the globe over the next century.

"Extrapolating the results of this study for this purpose would only provide speculations not based on evidence," Gasparrini said. However, he has received a grant from the United Kingdom to study that and hopes "we will answer this question soon," he said.