Combating the health impacts of extreme heat
Measuring and communicating the risks of extreme heat is to key to mitigating its impacts on health—but is surprisingly difficult to do, experts told an audience at ScienceWriters2024. (Illustration by Erin Cafferty)
In the aftermath of Hurricane Helene, it’s easy to see why natural disasters take center stage in policies addressing climate-related health risks. But the focus on catastrophic impacts overlooks growing long-term consequences of climate change, like extreme heat, said Ashley Ward, director of Duke University’s Heat Policy Innovation Hub, during the Council for the Advancement of Science Writing’s New Horizons in Science briefings at the ScienceWriters2024 conference Nov. 9 in Raleigh, N.C. “Most heat-related illness is cumulative. Most heat exposure is chronic.”
In the United States, heat is now a chronic health risk, killing more people than any other weather-related event. Not only are summer daytime temperatures reaching record highs, nights are also becoming hotter, reducing the time people can recover from daytime heat.
Despite the danger, it is surprisingly difficult to measure and communicate the risk of extreme heat, Ward said. The National Weather Service uses the heat index (the “feels like” temperature), which is based on air temperature and relative humidity, to determine when to issue extreme weather warnings. However, “heat index is actually not the best thing to measure risk, or heat stress in the body,” said Ward, adding that often the warnings are issued “many degrees later than we are actually at risk.”
The most accurate heat risk measurement is the Wet Bulb Globe Temperature (WBGT), which was created by the U.S. military in the 1950s. It uses three thermometers to measure the effects of sunlight, wind speed, and humidity on the temperature. Sports teams use the WBGT to assess the heat risks of playing outdoors. According to Ward, using the WBGT on job sites could drastically decrease the health burden of heat on outdoor laborers.
Another issue is poor communication of heat risk. Frequent heat advisory warnings can desensitize people living in hot climates, causing them to ignore actual extreme heat. “Heat exposure is going to look different depending on where you are,” said Ward, who encouraged government officials to “think regionally” when designing policies. Warnings should be based on whether the temperature is a “departure from normal” for the area, rather than from the national average.
There is no one-size-fits-all approach to reducing heat risk. Policies to mitigate heat risk should also take into account regional differences in finances, population density, and demographics, Ward said. The key is to engage and trust residents of the area. “Communities have long identified heat as a problem,” said Ward, and are “just waiting for the rest of us to catch up with them.”
