During hot weather, daily activities such as walking and gardening can become dangerous. Such obstructive heat has become much more common around the world, researchers report March 10 in Environmental Research: Health.
Using global heat, humidity and demographic data, scientists found that sweltry conditions now limit light physical activity for adults ages 18 to 40 for about 50 hours a year, on average. That’s double what young adults faced from 1950 to 1979. Meanwhile, adults over 65 now experience an average of about 900 hours of activity-limiting conditions each year. That’s more than 10 percent of the year and 300 more hours than half a century ago.