High heat is especially dangerous for many people, from the elderly, to small children, to those who work outdoors for prolonged periods of time, says Dr. Samuel Eldrich, medical director of the Emergency Department at Temple Health-Chestnut Hill Hospital.

And if it seems hotter than ever out there, it’s not just you.

2024 was the world’s hottest on record, according to the European Commission’s Copernicus Climate Service, the United Kingdom’s Meteorology Office, and Japan’s weather agency. This year is expected to be one of the five hottest ever recorded, a report by NOAA’s National Centers for Environmental Information indicates.

Locally, with the exception of a recent and blissfully welcome break in the heat, Philadelphia continues to experience record high temperatures, with recent heat indexes (heat, plus humidity) soaring above 100 degrees. These warmer summers with their extreme heat warnings are “consistent with climate change,” Gregory Jenkins, a professor of meteorology and atmospheric science at Penn State University, told WHYY in a 2022 story. “It looks like this is what we will continue to see over time.”

Throughout this summer, Eldrich said he has seen and treated many instances of heat-related illness at Temple Health-Chestnut Hill Hospital. “Most of the time, people are wise enough to catch it when they start to get dehydrated,” he says, “but with the excessive heat sometimes comes dizziness, muscle aches, nausea, fast heart rate — and that’s when people come into the emergency department, where we’ll do a complete workup, and most importantly, cool them down and get them fluids and rehydrate.”

The elderly are particularly vulnerable, he explains, “but really, it’s anyone who can’t escape the heat and doesn’t hydrate properly. If you’re younger and healthier you can tolerate it more. So, it’s definitely the elderly who are most prone to dehydration and everything else. The elderly just don’t have much reserve. Even the smallest things can throw them over. For example, small urinary tract infections and other infections can cause issues. It’s the same thing with small amounts of fluid loss. That can cause more profound dehydration, kidney issues and other concerns.”

Prolonged exposure to heat and its all too frequent companion, humidity, can increase the body’s core temperature and reduce the ability to dissipate that heat through sweat. That, in turn, causes dehydration, the main threat to health. It can even be life threatening.

From the standpoint of medical professionals, the body’s response to heat can range from heat cramps, to heat exhaustion, to heat stroke, which can be fatal.

“The least serious is essentially prolonged heat exposure in which you can just get very weak or tired from the heat itself,” Eldrich said. “The most common is probably when you have prolonged heat exposure that then causes dehydration from the excessive fluid loss through sweating. From there, you can get dizziness, increased heart rate, nausea, vomiting, and muscle cramps. If you have more prolonged exposure than that, you can get heat exhaustion or heat stroke, and you can have altered mental status, confusion, extreme lethargy or weakness. And that’s usually when people end up in the hospital with complications. It’s all on a spectrum. It goes from feeling just a bit overheated all the way to loss of consciousness.”

So, let’s take a closer look at that spectrum, from the least serious to the most. There are three heat-related concerns in particular.

Signs to watch out for

Heat cramps: As the name suggests, the main sign is muscle cramping and abdominal pain.

Heat exhaustion: This is when the body loses excess water and salt through sweating. Look for profuse sweating, moist and cool skin, weak rapid pulse, cramps, nausea, and dizziness.

Heatstroke: The most serious of the heat-related illnesses. Symptoms include rapid heart rate, dry or slightly moist skin, body temperature above 104 degrees, headache, nausea, and vomiting, and flushed skin. This is a true emergency. The longer the symptoms persist untreated, the greater the likelihood of severe illness or death. Contact 911 if you suspect heatstroke.

Protect yourself

What can you do to reduce your chances of becoming ill from heat exposure?

Stay hydrated. If you have to be outside — on a road crew, landscaping, or roofing, for example — drinking water or electrolyte drinks like Gatorade or Pedialyte is essential as the heat becomes intense, Eldrich said.

Caffeinated and alcoholic drinks are not a safe substitute for just plain water. Caffeine is a stimulant and a diuretic. It makes you urinate more, contributing to fluid loss, and both are unhelpful in preserving optimal body temperature in the heat. Alcoholic drinks impair your body’s ability to regulate temperature. So, while an ice-cold brewski or two might seem like just the ticket after a long afternoon of yard work in high heat, bear in mind that booze can significantly increase the risk of heat exhaustion or heatstroke.

How much fluid is enough? “It’s really hard to say because it all depends on your exposure and how much you’ve been sweating,” Eldrich said. “It’s really more listening to your body, making sure your lips aren’t dry, you’re not feeling excessively thirsty, you’re not feeling dizziness – things like that. Each person is different. It all depends on your exposure. It could be 10 bottles; it could be two.”

Cool down. Moving to an air-conditioned area is optimal. If you don’t have air conditioning, fans can be useful, Eldrich said. “It’s not the most ideal situation, but anything you can do to cool down a bit, whether it be fans, ice packs, or spraying yourself with a water bottle, will help with some of that evaporative cooling.” He also says it’s especially important to keep cooling throughout the day because the ill effects from heat exposure can build up over the hours.

“Even if you don’t have air conditioning in your home,” Eldrich said, “find a place that does — a grocery store, library, a city cooling center, the mall. Any place where you can get air conditioning, even if it’s just for 20 minutes, cools your core temperature and resets you.”