According to a study from Hokkaido University, heat waves and cold spells come with different health risks. The researchers found that extreme cold increases the risk of illness and death among people with cardiovascular and respiratory diseases, while extreme heat is risky for people with renal diseases.
“We analyzed the data from Twin Cities, Minnesota, in the U.S., and found patterns with universal validity across the globe,” said lead author Matteo Convertino.
Extreme weather events are known to be dangerous to human health, yet not enough research has been focused on how specific temperatures affect morbidity and mortality. This insight would be critical in tailoring public service messages for people with specific health conditions.
Professor Convertino teamed up with experts at the University of Minnesota Twin Cities and the Minnesota Department of Health to investigate which public health warnings should be given ahead of hazardous temperatures.
In the Twin Cities, the winters are harsh while the summers are hot and humid. The researchers obtained extreme temperature data and compared it to deaths in the city between 1998 and 2014. They also compared temperatures to emergency room visits from 2005 to 2014.
The experts noted that the relative risk for mortality and morbidity increased with more extreme temperatures, but at-risk populations were affected differently depending on their health conditions.
There was a higher risk for people with cardiovascular disease or respiratory illness in the winter but not in the summer, and the opposite was found to be true for patients with renal diseases. In addition, diabetics showed no significant response to extreme temperatures.
The findings of the study also indicate that heat index and percentile-based temperature thresholds are more useful than absolute temperatures for determining when public health warnings should be issued.
“Considering climate variability over space and time, tailored emergency risk communication programs are extremely important for informing the general public about potential health risks, such as severe heat waves or cold snaps, and how individuals can protect themselves,” said Professor Convertino.
“Our model can determine such temperature thresholds to start risk communications, which is important for saving human lives.”
The study is published in the journal Risk Analysis.