VGS   How does heat harm us? Who is at risk and how can you protect yourself? Hello and welcome to Science in 5. I'm Vismita Gupta-Smith. We are talking to Dr. Joy Shumake-Guillemot. Welcome, Joy. Joy, talk to us about how heat harms us.

JSG   Well, when we're exposed to hot temperatures for too long, the body is naturally going to want to try it and cool itself. And so it's going to kick in to a biological process where the skin is going to send a signal to the brain to dilate the blood vessels and try to get rid of this excess heat. And if that doesn't work, then the body is going to start sweating. And if that doesn't help enough, well, your temperature's going to continue to rise. And with an increasing internal temperature, then you're going to start to experience symptoms of heat exhaustion.

You're going to feel weak, you're going to get dizzy. You may have headaches and you may even feel nauseous. So unfortunately, there are limits to how fast and how much your body can actually cool itself. There is a certain point that it actually can become overwhelmed. And this is where the state of heat exhaustion can advance to become heat stroke, which is a medical condition that requires immediate medical intervention to cool the body.

VGS   So Joy we know that the older people and younger infants are especially vulnerable, but actually we are all at risk right? So talk to us about who is at risk from extreme heat.

JSG Well, that's right. Older people are more vulnerable to heat illness. And that's because the aging body is less capable of getting rid of this excess heat. However, those that are also at risk are outdoor workers, pregnant women, children and infants, people with underlying medical conditions that affect the heart, the lungs and the kidneys, as well as people who are isolated. We also see worldwide that people who are experiencing poverty as well as homelessness are disproportionately affected by heat, particularly in dense urban areas.

But we have to keep in mind that even young and healthy people can be impacted by heat. If you're exercising outdoors when it is too hot, you can be affected. Workers who are out in the heat for long periods of time can be affected. And this is because the working muscles are creating additional heat in the body and the body has to work twice as hard to get rid of this additional heat. We also see a hotspot for cases of heat illness happen to be at festivals and outdoor gatherings like music concerts, where people have underestimated how long they're going to be out in the heat and they're unprepared and they do fall sick from these conditions.

Worldwide we know that people underestimate their own vulnerability to heat. The reality is we are all at risk of heat illness if we are exposed for too long to too hot conditions.

JSG   Well, we need to know the signs and symptoms of heat exhaustion and heat stroke and really take these seriously. And it's important during the heat season when it's hot outdoors that everybody thinks about their personal heat plan for the day. How am I going to stay hydrated? When do I need to stop and take a rest or go find some shade? Do I need to wet my skin to keep it cool? What do I need to do to keep myself cool and healthy during a hot day? It's also important to remember that you don't have to be outside, you can actually get sick from heat indoors as well as at night because it's quite often that indoor temperatures can be hotter than outdoors. So the safest space is actually going to be in the shade outdoors. And for people who don't have cooling, the use of a fan is definitely an important tool to reduce indoor temperatures, except in really hot conditions when it's over 40 degrees, 104°F, then using a fan can actually make things worse and can accelerate heating in the body instead of cooling it down.

It's also really important to check on others. Make a phone call to people who are vulnerable and make sure they have what they need. Make sure that children are hydrated and taking rest when they're playing outdoors. Make sure that infants in baby strollers are actually covered with a wet cloth so that the temperatures aren't becoming too hot and overexposing them. The good news in all of this is that heat- related illness and death is preventable. If people are aware of the signs, they know that they are vulnerable and they know the good behaviors and actions that they can take to keep themselves safe and healthy when it's hot outdoors.

VGS   Thank you, Joy. There you have it. How heat harms you and how you can protect yourself. Until next time, then. Stay safe, stay healthy, and stick with science.