Deadliest weather revealed: It's not what you might think
Thursday, May 21, 2015, 9:29 AM - Cold weather is responsible for killing 20 times as many people as hot weather, according to a new global study.
The findings also revealed that prolonged exposure to moderately hot or cold weather kills more people than extreme heat waves or cold spells.
Published in the Lancet medical journal, the study collected data from 384 locations and analyzed over 74 million deaths in various periods between 1985 and 2012. Mortality, weather variables and air pollution measures were all used to calculate the temperature of minimum mortality, the optimal temperature and to quantify total deaths due to non-optimal ambient temperature in each location.
A wide range of climates were evaluated from cold countries such as Canada, Sweden and UK, to areas in the Mediterranean, tropical and subtropical areas such as Brazil, Taiwan and Thailand.
High and low temperatures have been associated with increased risk for a wide range of cardiovascular, respiratory and other causes, suggesting the existence of multiple biological pathways, according to the study. As a result, this information is key in understanding health effects for planning suitable public health interventions and reliable predictions for climate change effects, the study notes.
The total fraction of deaths caused by non-optimal temperatures was 7.71 per cent, compared to that of extreme temperatures, responsible for less than one per cent of all deaths.
The study found that cold was accountable for most of the burden with a total estimate of 7.29 per cent, while heat attributed to 0.42 per cent of deaths.
Numbers varied substantially between countries, ranging from around 11 per cent in China, Italy and Japan with the highest attributable risk, to three per cent in Thailand, Brazil and Sweden.
"Current public-health policies focus almost exclusively on minimizing the heath consequences of heat waves," lead author Dr Antonio Gasparrini from the London School of Hygiene and Tropical Medicine told The Telegraph.
"Our findings suggest that these measures need to be refocused and extended to take account of a whole range of effects associated with temperature."
Experts in global and environmental health weighed in on the findings noting factors such as socio-economic status and age were not included in the analysis.
"Since high or low temperatures affect susceptible groups such as unwell, young, and the elderly people the most, attempts to mitigate the risk associated with temperature would benefit from in depth studies of the interaction between attributable mortality and socio-economic factors, to avoid adverse policy outcomes and achieve effective adaptation,"said Keith Dear and Zhan Wang, from Duke Kunshan University in China.