Hot and humid conditions now severely limit daily activities, especially for older people
In hot weather, everyday activities like walking and gardening can become dangerous. Such obstructive heat has become much more common around the worldthe researchers report on March 10 in Environmental research: health.
Using global data on heat, humidity and demographics, scientists found that sweltering conditions now limit light physical activity for adults aged 18 to 40 for about 50 hours per year on average. That’s double what young adults faced between 1950 and 1979. Meanwhile, adults over 65 now experience an average of about 900 hours of activity-limiting conditions each year. This represents more than 10% of the year and 300 hours more than half a century ago.
“We’re seeing a substantial decline in the number of hours older adults can safely perform general tasks,” says human biometeorologist Jennifer Vanos of Arizona State University in Tempe.
She and her team combined heat and humidity data from 1950 to 2024 with simulations of the ability of healthy, acclimated adults to regulate body temperature in the shade, as well as population and development information from nearly 200 countries. The researchers then identified when and where heat and humidity made it unsafe for adults of different ages to engage in moderate physical activities, or more strenuous ones than walking to the market or sweeping a doorstep. “This is no way to live,” Vanos said.
Hours to lose heat
This map shows the number of hours per year that sweltering conditions limited older people in different countries to light physical activity, such as walking at a moderate pace or light to moderate housework. Older adults who engaged in more strenuous activity during these hours could be at high risk of heat-related illnesses, such as heat stroke, and even death. Switch between the two time periods to see how exposure to obstructive heat has changed for adults over 65 in nearly 200 countries over the past half-century. Use the search bar to focus on a country that interests you.
Nearly 80 percent of the world’s population lives in places where heat and humidity severely limit activities. elderly people for part of the year, the researchers found. Countries in South and Southeast Asia as well as the Middle East face the greatest annual exposure. In Thailand, for example, older people now face an average of nearly 2,200 hours of obstructive heat, up from about 1,600 hours between 1950 and 1979. In Qatar, older people now experience more than 2,820 such hours a year, up from about 2,270 half a century ago.
In the meantime, in the United Statesolder adults now face an average of about 270 hours per year in unsafe conditions, an increase of about 70 hours. However, these figures can vary considerably from one community to another, due to the diversity of the country’s environments.
Even in developed countries like UNITED STATES and in Qatar, vulnerable groups – such as external workers And people with comorbidities – might lack the resources to deal with the heat, Vanos says. “Their habitability, their ability to work and play, and even to be productive members of the population on very hot days, is extremely compromised. »
