As cities and towns around the nation log record-high temperatures, medical personnel and physicians may encounter Heat-related illness more frequently.

MedPage Today spoke with Spencer Solomon, a U.S. park ranger and the emergency services coordinator for Death Valley National Park’s dedicated team of emergency medical technicians, who operate in the some of the hottest temperatures in the country — and the world.

In the 10 years leading up to 2020, Death Valley had the highest recorded maximum “normal” temperatures of any of the more than 6,000 weather stations spread out across the U.S., and holds the world’s highest air temperature ever recorded, at 134°F in July 1913.

The park, located in Eastern California straddling the state line with Nevada, spans an area about the size of Connecticut and is known as the hottest place on Earth. “It’s only bad probably 3 months out of the year,” Solomon said, although temperatures already broke 120°F last week.

Heat Emergencies

Heat illness can range from more common signs of heat exhaustion — like nausea, fatigue, dizziness, weakness, and rapid pulse — to emergent symptoms of heat stroke: confusion, slurred speech, agitation, loss of consciousness, and seizures. In extreme situations — confusion during a quick “mental status assessment” is the most telling sign — Solomon said his team call for a medical evacuation by helicopter to a nearby hospital.

His team, which has two ambulances, gets about 10 heat-related emergency calls per month in the hottest months of June, July, and August.

But this is likely an underestimate of heat-related illness, Solomon noted: “Of the people that are visiting, how many of them are actually reporting that they’re ill and calling for help while they’re here?” The park, he said, had 90,000 visitors in June. It averages about one to three deaths where heat played a role each year.

The park’s unique mix of heavy tourism, remote location, and dry heat mean the park’s medical team has its heat protocol honed to a science.

Overall, prevention and response to heat-related illness may vary under different circumstances. Urban settings may have more older, lower-income, and minoritized racial and ethnic groups who are more susceptible to heat-related illness, but who may live closer to medical facilities. The CDC recommends that jurisdictions where structural inequities endanger certain groups should take steps to increase access to cooling stations, green space, and air conditioning.

For the untrained, there are a number of unexpected lessons on how heat can affect both patients and responders.

Heat Acclimatization

Many visitors to Death Valley in the hottest months come from Europe and Asia; tourists come specifically to experience the extreme heat, posing with the giant thermometer outside the visitor center, Solomon said. One visitor even told him she had never experienced anything hotter than 78°F, he noted. But many people don’t know that, like high altitudes, “your body can acclimate to heat through exposure, and it usually takes a few days to get used to the 120-degree weather out here,” he added.

Solomon’s team has an employee policy that spells out the number of days they must work at reduced outdoor exposure depending on how many days they have been away from the heat environment, in order to re-acclimate. Employees who took a vacation for 7-14 days in a different climate may take 4 days to gradually increase exposure before they spend a whole work day outside, for example.

“The responders have to take care of ourselves as well,” Solomon noted.

Sometimes, heat can even prevent an emergency rescue. If the exact location of the person is unknown and temperatures are above 110°F, rescuers must wait until 30 minutes before sunset to begin searching for their own safety. In these temperatures, Solomon said, the air can be too thin for helicopters to take off.

Prevention and Diet

Preventing heat-related illness is about more than proper hydration while out in the sun. “I don’t think a lot of people realize if you’re going to do physical exercise or you’re going to be out in the heat, you need to be hydrated prior to when you’re going out,” Solomon said.

According to Death Valley National Park’s Heat Stress Policy for employees, hydration 24-48 hours prior to heat exposure and 24 hours after is key, and ensures that your body can produce enough sweat to cool down.

There’s a saying that when out in extreme heat, “if you’re thirsty, then it’s too late,” Solomon said. The employee policy advises that people should drink 24-32 ounces of water per hour in high heat.

“People are driving in 2 hours from Vegas, spending an hour and a half hiking when it’s 120°, with a 12-ounce water bottle … didn’t eat, haven’t been drinking,” he said. “Heat exhaustion will definitely creep up on you.”

Solomon also recommended salty snacks while out in the heat, or other forms of electrolyte replacement, although he warned that if someone is already experiencing heat illness-related symptoms, drinking a beverage like Gatorade too fast can introduce sugar too quickly into the body and lead to vomiting.

Delayed Heat Exhaustion

Solomon says heat-related emergency calls in the hottest season tend to follow a curious pattern: “There’s kind of two periods or two times of day that [calls] will come in.” One is midday; for example, someone on a trail might be experiencing heat exhaustion. But the next wave comes late at night, around 10 p.m. or later, “after people have spent the entire day hiking. And then they get back to their hotel — if they’re staying here in the park — realize they’re feeling ill, and start to develop some of the symptoms of heat stroke.”

Solomon said progression of heat-related illness over many hours can happen if someone has been exposed to outdoor heat for longer periods of time, or hiked extensively during the day. The park has stop signs posted on trails that warn “extreme heat danger/walking after 10 AM not recommended,” but not everyone complies.

According to the CDC, heat exhaustion can develop even several days after exposure. The Mayo Clinic, too, says prolonged periods of exercise can lead to heat exhaustion’s progression over time, instead of a sudden onset.

For heat-related emergencies, rapid cooling is the standard of care: immersion or dousing in cold water, removing clothing, applying ice packs, fanning, elevating feet, and monitoring airway and breathing. For milder cases, patients should seek shade or air conditioning, and sip cool fluids.