Dr. Juthamard Surapongchai is an Assistant Professor and lecturer in Exercise Physiology and Heat Health at Mahidol University, Thailand, specializing in human thermophysiology, heat adaptation, and cooling interventions. She is a member of the Heat Science Hotline board.
There is a surprisingly narrow temperature range in which the human body can function safely. For Dr. Juthamard Surapongchai, whose research focuses on how the body responds to heat, understanding that limit is critical.
“The important thing to keep in mind is core body temperature,” she explains. “A normal core body temperature is around 36.5 to 37.5°C (97.7 to 99.5°F). Below 32°C (89.6°F) is too cold, and above 40.5°C (104.9°F) is dangerously hot.” While illness can sometimes push the body beyond these limits, rising temperatures are making dangerous heat exposure increasingly common.
Working with vulnerable populations in Thailand—a country where high humidity can push the “feels-like” temperature above 52°C (125°F)—Dr. Surapongchai has seen how difficult it can be for people to recognize when familiar heat becomes dangerous. “Knowledge and awareness are very important. Thailand is a tropical country, so people are used to heat. But many don’t realize that it’s getting hotter every year, and that the human body has limits. Without that awareness, people don’t change their behavior.”
The Burning Question — What should practitioners and researchers be asking that they aren’t?
Despite growing awareness of extreme heat, Dr. Surapongchai believes one of the biggest scientific gaps remains understanding why the same temperatures can affect people so differently.
Throughout her research, one lesson has become increasingly clear: heat vulnerability is not determined by temperature alone. It reflects the interaction of biology, health, environment, behavior, and access to resources—all factors that can increase risk.
“Menopause is one factor because of hormonal changes, but it is only one piece of a much larger picture. Cardiovascular health, kidney function, heat acclimatization, fitness, and underlying medical conditions all influence how well someone tolerates heat.”
Biological sex can influence how the body regulates heat, though the differences are complex.
“Men generally have greater muscle mass, which generates more metabolic heat during physical activity,” she explains. “Women, however, experience hormonal fluctuations throughout the menstrual cycle and menopause that also affect body temperature and heat tolerance.”
Sweat response differs as well.
“Women generally have fewer and less active sweat glands, so sweating may be less efficient. But vulnerability is never determined by one factor—it’s always the interaction of many.”
The Surprise — What have you learned in your own work that challenged your assumptions?
One of the biggest changes Dr. Surapongchai has witnessed is how rapidly heat science has moved from a niche field to a global research priority.
“When I recently presented my work in Europe, I was surprised by how much interest there now is in heat-related research.”
Her research explores practical cooling interventions, including edible ice bars consumed before and during exercise to reduce core body temperature. The findings suggest that women may experience even greater cooling benefits than men, although hormonal changes—including different phases of the menstrual cycle and menopause—also influence individual responses.
The Underrated Fix — What’s a solution that deserves more attention than it gets?
One of the most overlooked ways to reduce heat risk, according to Dr. Surapongchai, is helping the body adapt before a heat wave ever arrives.
“Exercise. It’s good for all physiological systems — if your systems work well, that helps you overall. Exercise is one method of heat acclimatization, because it stimulates the sweat glands to work well and increases their sensitivity. It’s not just heat itself that affects people — it’s people who stay in air conditioning. When they’re exposed to heat, it’s much more serious for them. But people who exercise regularly — every day, every week — have a lower perception of heat compared to, say, an office worker who’s in air conditioning all day.
“I like to promote exercising in normal, non-air-conditioned temperatures — above 25°C, maybe up to 30°C — because that can improve heat acclimatization. When these people encounter higher temperatures or a heat wave, they have more tolerance than people who haven’t had that exposure.”
Hydration is another essential—and often overlooked—intervention.
“When you’re working in the heat, your body needs enough water to replace what you lose through sweating. If you’re dehydrated, your risk of heat stress increases.”
But staying hydrated is not always as simple as drinking more water.
Dr. Surapongchai points out that many outdoor, agricultural, and construction workers lack reliable access to clean drinking water or even basic sanitation facilities. Women are often disproportionately affected because inadequate bathroom access discourages them from drinking enough water during the workday.
The benefits for allowing hydration breaks are enormous, however. “A glass bottle manufacturer I worked with set up a water station where they provided their workers with a short break and access to water. This prevented their workers from getting kidney disease.
What is a question you want to be asked?
“I would like people to ask more about heat mitigation and heat acclimatization—how our bodies adapt to heat and what we can do to improve that process.”
Ultimately, Dr. Surapongchai hopes more people recognize that extreme heat is no longer a distant threat but a shared global challenge.
“Heat is an important problem that we can’t escape. We all have to help each other. If someone doesn’t have the knowledge to protect themselves, we should share what we know. If governments, organizations, and communities all work together to increase awareness and improve policies, we can better protect people from heat.”