Researchers have found that it isn’t just temperature extremes that pose risks to human health; sudden temperature changes can also increase mortality.
Very hot and very cold temperatures are known to exacerbate certain medical problems, like heart disease, and public health officials have observed more deaths during these periods in cities around the world.
Now new findings show that when the temperature changes drastically over the course of a few days, even without reaching extremes, it can harm the elderly, especially those with existing health issues. The report was published this week in the Proceedings of the National Academy of Sciences.
“I think that the issue is that we adapt physiologically to different temperature regimes,” said Joel Schwartz, professor of environmental epidemiology at the Harvard School of Public Health.
Schwartz, who co-authored the paper, said people who live in the tropics or other warm areas for long periods of time tolerate hot weather better than those who come to visit, showing no excess temperature deaths among their local population. The same is true for cooler regions of the world, like Scandinavia. And as seasons change, people acclimate to their new surroundings. “It takes on the order of weeks to get complete physiological adaptation,” he said.
But what happens when temperature shifts just a few days? To find out, the researchers looked at Medicare data, which cover Americans 65 and older, between 1985 and 2006 over 135 cities.