Unpacking the Detrimental Impact of Severe Heat on Human Health: An Expert Analysis

As the Southwestern U.S. braces itself for a continuous stretch of scorching temperatures, meteorologists issued extended warnings of extreme heat into the weekend for Arizona’s most densely populated regions, alongside advice for residents in parts of Nevada and New Mexico to remain indoors.

The metropolitan region of Phoenix is poised to either match or surpass a record dating back to the summer of 1974, marking the highest number of successive days with a peak temperature reaching or exceeding 110 degrees Fahrenheit (43 Celsius). Remarkably, even the temperatures registered at dawn are close to breaking historical records.

Near the U.S.-Mexico boundary, federal officials have noted that extreme heat during the past weekend had severe consequences, resulting in the rescue of 45 individuals and the death of another 10.

Given the ongoing wave of relentless heat, weather forecasters, medical professionals, and local health authorities across the Southwest are urging individuals to minimize their time spent outdoors and become familiar with the symptoms of heat-related illnesses.

SIGNS TO WATCH FOR

The potential symptoms of heat exhaustion and heat stroke, ranging from profuse sweating and lightheadedness to muscle cramps and even vomiting, are expected to become increasingly prevalent according to experts, due to anticipated future increases in temperature and frequency of heatwaves in the U.S.

Heat stroke represents the most severe of heat-related illnesses, occurring when the body loses its ability to produce sweat. Manifesting symptoms include skin becoming hot and red, accelerated pulse rate, headaches, nausea, confusion, and even loss of consciousness, as body temperature soars to 103 F (39 C) or beyond.

Dr. Jon Femling, an emergency medicine physician and scientist at the University of New Mexico, explains that the body attempts to counteract the heat by directing blood to the skin in an effort to cool down. But, as a person breathes more, they lose fluids, leading to increasing dehydration. Crucial electrolytes like sodium and potassium can also be lost through sweating.

The initial reaction to this, Femling elaborates, is muscle fatigue as the body begins to divert blood flow. This can subsequently lead to organ damage, impacting the kidneys, spleen, and liver. In extreme circumstances, the brain may not receive adequate blood flow, leading to severe consequences.

Understanding the symptoms of heat stroke in others is crucial, since individuals may not recognize their own peril due to a state of mental confusion.

In a heat stroke scenario, experts recommend calling 911 immediately and attempting to lower the person’s body temperature using cool, damp cloths or a cool bath.

With heat exhaustion, the body may become cold and damp. Additional symptoms can include profuse sweating, nausea, muscle cramps, weakness, and dizziness. The most effective response is to find a cool location, loosen clothing, and hydrate slowly.

Those at a higher risk during periods of high temperature include the elderly, children, and individuals with existing health conditions.

Cardiovascular collapse is one of the most common fatal consequences during extreme heat events, experts have noted, due to the additional strain placed on the heart to aid the body in coping with the heat.

To prevent heat-related illnesses, health officials advise staying indoors, finding air-conditioned spaces, and consuming more water than usual. Caffeine and alcohol should be avoided, and consuming smaller meals throughout the day can also be beneficial.

UNDERSTANDING THE LIMITS

Researchers at Arizona State University are seeking to improve our comprehension of how extreme heat affects the human body and what makes sweltering weather conditions so deadly.

They are utilizing a specialized thermal mannequin, known as ANDI, which is equipped with roughly three dozen different surface areas, each individually regulated with temperature sensors and designed to mimic human pores that produce sweat.

The objective of much of our research, explains Jenni Vanos, an associate professor at ASU’s School of Sustainability, is to gain a better understanding of how people respond to increasingly severe heat over extended periods and what proactive measures can be taken.

The thermal mannequin technology, of which there are only 10 examples globally, is usually employed by athletic clothing companies for testing purposes. ASU’s mannequin is the first to be designed for outdoor use, thanks to a unique internal cooling system.

ASU has also introduced a new “warm room” or heat chamber, where researchers can simulate global heat-exposure scenarios. Temperatures within the chamber can reach 140 F (60 C), and both wind and solar radiation can be adjusted for experiments.

Evaluating short- and long-wave radiation in the environment can also help researchers understand how much a surface—or a person—would heat up in a specific city location.

In such extreme conditions, the most crucial mitigation factor within an urban environment is shade, says Vanos, particularly in intensely sunny and hot areas like Phoenix. Shade significantly reduces the overall heat load on the human body.

SEEKING RESPITE

Residents across the region, with air conditioners and fans operating at full capacity, eagerly anticipate the onset of the monsoon season, hoping for a respite from the relentless heat.

However, the characteristic summer thunderstorms, which typically bring cloud cover, lightning, and downpours to the Southwestern desert, are notably absent due to the prevailing El Niño weather pattern, says National Weather Service meteorologist Sam Meltzer.

“It seems that the coming months will be unusually dry,” Meltzer notes, explaining that the likelihood of storms breaking the heatwave depends on wind patterns bringing moisture-laden air from the Gulf of California into Arizona, New Mexico, and Nevada.

“But that doesn’t mean there won’t be any thunderstorm activity,” Meltzer adds, “it may just be postponed.”

Meltzer, who transferred last winter to Las Vegas after working in Phoenix, observed that while Phoenix temperatures soared last month, southern Nevada experienced an unusually cool June.

The official daytime temperature at Harry Reid International Airport in Las Vegas stayed below 100 F (37.8 C) for a record-breaking 294 days before hitting 102 F (38.9 C) on June 30. This surpassed the previous record of 290 days, from 1964 to 1965, which had held for 58 years.

However, Vanos emphasizes that it’s not just the air temperature that poses a risk. High humidity levels can inhibit the body’s ability to produce sweat, which is a key mechanism for cooling down.

Contributors to this report include Big Big News writers Ken Ritter in Las Vegas and Walter Berry in Phoenix.

Frequently Asked Questions (FAQs) about Extreme Heat Effects

More about Extreme Heat Effects

• Understanding the Impact of Extreme Heat on the Human Body
• Heat-related Illnesses and First Aid
• Extreme Heat Preparedness
• Heat and Older Adults
• Climate Change and Heat Waves