“The heat will kill you first.”

That dire warning by environmental journalist Jeff Goodell became the title of his 2023 book, in which he describes how extreme heat due to climate change has killed thousands of people across the globe in our modern world. 

That fact underlined the focus of Saturday’s workshop Extreme Heat & Health: Clinical and Public Health Strategies for Prevention and Action at APHA 2025. 

Extreme heat kills more people in the U.S. each year than all other extreme weather events combined — and disproportionately affects vulnerable communities, said presenter Ben Fulgencio-Turner, director of the Climate for Health program at ecoAmerica. Extreme heat is also the No. 1 killer of people globally when it comes to extreme weather events. And the effects of extreme heat are increasing each year as temperatures continue to rise. 

Fortunately, most heat-related illnesses and deaths are preventable, Fulgencio-Turner said, through both individual planning and systemic solutions. The key is to develop action plans for you, your family, your community and to create and advocate for system-wide plans and policies. 

Saturday’s workshop also educated participants on the warning signs of heat exhaustion and heat stroke — and how to prevent and manage them — as well as how heat affects our bodies in ways you may not consider. 

The three-hour training was developed by Climate for Health and APHA’s Center for Climate Health and Equity. The free self-paced continuing education training is also available online. 

Heat-related deaths in the U.S. increased between 1999 and 2023, with a substantial rise from 2016 to 2023, according to a 2024 report in JAMA. Those numbers were likelier higher than reported because the study relied on heat being recorded as an underlying or contributing cause of death, said presenter Logan Harper, a physician at the University of Colorado who recently completed a Climate and Health Science Policy Fellowship in which he focused on extreme heat. 

Extreme heat can cause dehydration, heat stroke and mental health distress.  It can also aggravate cardiovascular and respiratory diseases and illnesses.

Our bodies have to work harder in extreme heat just to maintain a normal temperature, Harper explained, which can be dangerous for anyone but particularly for older adults, children, pregnant people, those with chronic conditions (heart disease, respiratory disease, kidney disease, diabetes), those with psychiatric conditions, outdoor workers, and historically underserved populations, including those living in urban heat islands. 

Numerous medications can also increase risk. These include diuretics, which pull extra fluid off the body; beta blockers, which reduce the heart’s ability to pump hard and fast; and antihistamines, which reduce your ability to sweat. “And many different mental health meds, like anti-psychotics, actually change your brain’s ability to regulate your body temperature and increase your likelihood of overheating in a heat wave,” Harper said. 

Heat exhaustion vs. heat stroke

Heat exhaustion and heat stroke are two different illnesses. Heat exhaustion symptoms can include heavy sweating, cool and clammy skin, muscle cramps, fatigue, rapid pulse, dizziness, headache, fainting and nausea.

“If people are in the heat and they start to just look or feel really sick, they probably have heat exhaustion,” Harper said. “That is an extremely important red flag.”

If heat exhaustion progresses, it can lead to heat stroke, which is critical. In fact, heat stroke has a mortality rate of 33% to 80%, Harper said. 

Heat stroke includes a body temperature of 104 F or higher, dysfunction of the central nervous system — which could cause seizures or disorientation — and dry skin with no sweating. Heat stroke can affect almost any organ, Harper said. He pointed out that even the intestines — which lay people may not associate with heat stroke problems — can leak toxins into the bloodstream and cause sepsis. 

Cooling down a person immediately is the best treatment when they are overheated. But, of course, prevention is a better solution. Individuals should develop heat action plans for themselves and loved ones, knowing how you will deal with extreme heat when it occurs. 

Becoming a climate ambassador

Organizations and communities can develop extreme heat action plans using the BRACE framework (Building Resilience Against Climate Effects), which was developed in 2011 and updated in 2024. APHA and ecoAmerica offer a free on-demand BRACE training. BRACE includes six elements: get ready, stay ready; partner; listen and assess; investigate options; prioritize and plan; and take action. 

The presenters encouraged public health professionals to become climate ambassadors and get involved in spreading the word about extreme heat, while helping communities develop solutions to better deal with heat effects. Check out APHA’s Extreme Heat Resource Hub and new podcast series, The Heat Rx. 

Climate ambassadors foster impactful climate conversations, inspire others to get involved in climate action and advocacy, take steps to act and advocate for climate solutions, and take civic actions, Fulgencio-Turner said. 

“As health professionals, you are trusted voices and the more you talk about extreme heat with those around you, the safer and healthier our communities are going to be,” Fulgencio-Turner said. 

Photo courtesy EZ Event Photography.