By Amy Norton
WEDNESDAY, October 13, 2021 (HealthDay News) – Urban dwellers around the world are sweat A new study suggests that they did three times as many days of ‘extreme heat’ as their counterparts in the 1980s.
The study is the latest to determine the increasing exposure of humans to dangerously high temperatures of humans. Experts say they are looking at what is happening in finer detail than previous research has done – and this suggests that exposure to extreme heat is more widespread than previously thought.
According to researchers, 1.7 billion urbanites — or nearly one-fifth of the planet — were exposed to an increasing number of heat days between 1983 and 2016.
These are the types of temperatures that increase the risk of heat illness, even for healthy people when working out or exercising outdoors.
For people living in hot cities, ‘it’s not news that it’s getting hot,’ says study leader Cascade Tuholske, a research scientist at Columbia University’s Earth Institute in New York.
It’s not just that urban areas are the only place that feels heat, says Tuholske, who was a graduate of the University of California, Santa Barbara, at the time of the study.
But cities are sizzling due to a combination of two factors: climate change and what is called the urban heat island effect. This is where a lack of grass and trees and an abundance of concrete and asphalt come together to absorb heat.
In addition, more of the world’s population is moving to urban centers – which, according to Tuholske’s team, was an additional reason for the growing exposure to extreme urban heat.
The findings, which was recently in the Proceedings of the National Academy of Sciences, is based on data from more than 13,000 cities around the world. Researchers estimate the population’s exposure to days of extreme heat – defined as a “wet bulb” temperature of 30 degrees Celsius (86 degrees Fahrenheit) or higher.
It is a measure that not only takes into account temperature but also humidity, wind speed and cloud cover. It gives an idea of the “feel like” temperature for people who are in the sun.
If the wet bulb temperature reaches the 30 C threshold, a healthy person will feel heat stress after 30 minutes of work exercise according to the U.S. National Weather Service.
“It’s not just older people who are affected,” Tuholske remarked.
His team estimates that people in urban areas had a 200% increase in exposure to extreme heat during the study period. But the impact was not uniform: 25 urban areas accounted for a quarter of the increase in extreme heat exposure.
The top four were: Dhaka, Bangladesh; Delhi, India; Kolkata, India; in Bangkok, Thailand.
Yet the problem was widespread, with almost half of the urban areas showing an increase in residents’ exposure to extreme heat.
The findings highlight the importance of gathering finer details about what city dwellers actually experience, according to dr. Mona Sarfaty, Head of the Climate and Health Program at George Mason University in Fairfax, Va.
Some innovative projects are aimed at that, she said. In Miami, for example, researchers armed ‘civil scientists’ with heat sensors to detect the temperature they encounter in daily life. At one bus stop, Sarfaty noted, the average temperature was 100 degrees Fahrenheit.
While global warming needs to be addressed with broad changes – including less dependence on fossil fuels such as oil and coal – local measures are also important, Sarfaty and Tuholske said.
Cities can create more ‘green spaces’,’ Sarfaty said, not only to provide shade, but also to cool the air. In some cities, such as Phoenix, special asphalt coatings are applied to reduce the temperature of hardened areas.
Local health departments and employers can also do more to spread awareness, Sarfaty said. She pointed to a recent study in Texas, where a ‘heat stress awareness program’ was found to reduce heat-related illnesses among city employees who worked outside.
“People are not necessarily aware of how quickly they can succumb to heat,” Sarfaty explained.
As with so many health conditions, Tuholske said low-income and marginalized people are one of the most vulnerable, as they often work outside and do not have air conditioning and other options to mitigate their exposure to dangerous heat.
There is a particular concern, he noted, for people living in cities around the world that were simply not meant to sustain the large population they now have.
The World Health Organization has more about climate change and health.
SOURCES: Cascade Tuholske, PhD, Postdoctoral Research Scientist, Earth Institute, Columbia University, New York City; Mona Sarfaty, MD, MPH, Director, Program on Climate and Health, George Mason University, Fairfax, Va .; Proceedings of the National Academy of Sciences, online, October 4, 2021