“I’ve been down here far too many years,” Shy said with resignation but no self-pity. “It’s not a pretty sight.”

Arms crossed, the 40-year-old Oregon native stood in front of the rough shelter she had built out of plastic tarps, discarded carpets, and a piece of felt the size of an SUV, all attached by carabiners and twine to an old Coleman tent with holes in the side.

But Shy wasn’t talking about the other jury-rigged structures, beater bikes, or scattered piles of trash surrounding her. She was referring to the daily struggle to survive in the heart of “the Zone,” a long, hot stretch of mostly shadeless streets and parking lots west of downtown Phoenix, where between 600 and 1,000 unsheltered people were living. At the time, it was one of the largest homeless encampments in the United States.

Shy, whose last name we’re not publishing for privacy reasons, said she was on a waiting list for subsidized housing and hoped to get a place soon. Asked how long she’d been waiting, Shy hesitated while doing the math. “I signed up three years ago,” she said.

This was in early May and the temperature already hovered around 100 degrees Fahrenheit. Shy was dressed for the heat, wearing a gray Calvin Klein sports bra and light-colored shorts held up by a colorful knotted scarf. In two months it would get far hotter, up to 119 degrees.

When I asked her what she would do about the caldron Phoenix would soon become, Shy shrugged. “It’s just going to get harder,” she said.

An ‘invisible killer’ — especially for unhoused populations

The homeless are usually the first to die.

In April, 46-year-old Crystal Gradilla, an unhoused woman, became the city’s first recorded heat-associated death of the year, when the temperature in Phoenix hit 99 degrees for the first time in 2023.

Although Phoenix is known as America’s hottest large city, people experiencing homelessness are dying in cities throughout the U.S. as climate change caused by burning fossil fuels results in record-breaking heat waves.

And even before the global average temperature set a new record high on July 4 and a massive heat dome over the entire Southwest sent temperatures soaring from California to Texas, extreme heat was already killing more Americans annually than any other natural disaster.

For decades, heat-related deaths were notoriously undercounted, according to Kristie Ebi, a professor of global health at the University of Washington. But she said newer studies based on epidemiological computer modeling are far more accurate.

The largest such study determined that between 1997-2006 there were some 6,000 heat-related deaths annually among the 62% of the total U.S. population included in the study. Another study, using more recent data (2010-2019), and extrapolating to include 100% of the total U.S. population, put the number of annual heat-related deaths at about 12,000. Drew Shindell, lead author of that study, explained that warmer temperatures during the period studied likely explain the higher total.

Experts often call extreme heat a “silent” or “invisible” killer because, unlike natural disasters such as tornadoes, floods, and hurricanes, heat waves aren’t telegenic. There are no swaths of destruction or raging rivers filled with bobbing cars.

The heat-related deaths of people living on the streets are doubly invisible. In addition to the factors above, the public at large tends to look away from the poorest of the poor even under the best of circumstances. When they’re actually dying on our streets, the need to look away is nearly impossible to resist.

For most Phoenicians, the summertime scurry between air-conditioned car and air-conditioned house or office is merely a nuisance, one that’s outweighed by the mild weather and cloudless blue skies during the rest of the year.

For the 15% of residents living below the poverty line here, however, summer is a fraught season. Many low-wage earners work outside in the heat, in construction or landscaping, and when they come home, running an air conditioner (if they have one) long enough for their bodies to recover from the day’s heat may be a budget-buster. Because heat stress is cumulative, when they go to work the next day, they’re more likely to suffer from heat illness.

Bad as that is, for those living on the street, the heat is a merciless killer.

The risk of a heat-related death is two to three hundred times higher for people living unsheltered than for the population at large, according to David Hondula, director of the city’s first-in-the-nation Office of Heat Response and Mitigation.

In 2022, a record 425 people died from heat in the greater Phoenix metro area. Of the 320 deaths for which the victim’s living situation is known, more than half (178) were homeless.

When unsheltered also means untreated

“The reasons for the high rate of heat-related mortality for the people we see go far beyond simply being without a home,” Dr. Mark Bueno said.

Bueno is outreach medical director at Circle the City, a nonprofit aid group that focuses on the city’s homeless population. This May we spoke in one of the organization’s five mobile medical units — air-conditioned trucks converted into rolling doctors’ offices. This one was parked in the Zone on a day when the temperature reached 103 degrees.

Bueno said that lack of regular medical care is a key factor behind many heat-related deaths in the Zone. If you’re living on the streets and your doctor is two or three miles away, he explained, you likely don’t have a car or other transportation to get treatment.

“You have to walk,” Bueno said. “If it’s 110 degrees outside, it might not happen.” The same applies to filling prescriptions. In the summer, many unhoused people aren’t able to get the medicines they need. “People die because they can’t reach a doctor or a pharmacy,” he said.

“Pretty much every medical disease you could think of is exacerbated by extreme heat,” Bueno said, including, most notably, cardiovascular and respiratory disease and diabetes.

Even those who manage to get treatment are at heightened risk. People diagnosed with heart failure, for example, are often prescribed diuretics. In extreme heat, it’s hard enough to replace water lost to sweat, especially if you’re unsheltered. The inability to stay sufficiently hydrated coupled with the water loss caused by diuretics can lead to acute kidney injury and possibly death.

Read: Common medications may increase the dangers of heat waves

Earlier in the Zone, Timothy, a 33-year-old man who had been living on the streets for four years, spoke of his experience with dehydration in the summer of 2022. “It got hot as hell out here,” Timothy said, “and one day I fucking passed out. I woke up in the hospital with tubes in my arm. They kept me there for like two weeks.”

When I asked Bueno about Timothy, the doctor shook his head and said, “Younger people with extended hospital stays because of dehydration are often suffering from rhabdomyolysis.” That’s a condition in which heat stress kills muscle tissue, flooding the bloodstream with large proteins and electrolytes.

“It’s treated with IV fluids,” Bueno said, “but recovery can take a long time. And sometimes the kidneys may be permanently damaged.”

If that’s what happened to Timothy, another bout with extreme heat could prove fatal.

Heat may intensify mental health issues

Extreme heat can also intensify challenges for unhoused people living with mental health conditions.

More than 20% of Americans struggling with homelessness have been diagnosed with severe mental illness, compared to about 5% of the total population.

A March 2023 study in the journal GeoHealth looked at the correlation between chronic diseases and deaths during the 2021 record-shattering extreme heat event during which 619 people died in British Columbia, Canada.

The study concluded that people who had been diagnosed with schizophrenia were three times more likely to have died than those who hadn’t received that diagnosis. People suffering from depression were also found to be at elevated risk, although the association wasn’t as strong as with schizophrenia.

Drug use and extreme heat: A life-threatening mix

The risk of dying in the heat increases dramatically for all populations when drug use is involved. According to the Maricopa County Department of Public Health, illicit drugs were involved in 55% of all heat-related deaths in 2022, a figure nearly five times higher than a decade ago, reflecting the ongoing opioid crisis ravaging all segments of American society and rising temperatures.

“There’s a stereotype that all homeless people are on drugs and abusing the system,” said Dr. Jack Palmer, a longtime emergency room doctor who now focuses on treating unhoused patients in Phoenix. Palmer admitted to holding some of the same biases before becoming the outreach physician for Circle the City in 2022.

“It’s been an eye-opening experience,” he said. “The stereotype couldn’t be further from the truth. They’ve fallen on hard times, often because of a lack of affordable housing.” Many of his patients were recently evicted because they couldn’t afford skyrocketing rents. “It’s heartbreaking,” Palmer said. “The person on the corner is just like you and me.”

Studies show that people experiencing homelessness are more likely to struggle with drug addiction. The reasons, however, are complex, Palmer said. “They may be self-medicating to treat the extreme stress of being homeless,” he said. And a higher percentage of that population experienced violent trauma before becoming homeless, which is also correlated with drug addiction.

Whatever the cause, the combination of drug addiction and extreme heat is exceptionally dangerous.

“Don’t do drugs because you will die,” was how James Burressput it when we talked inside the spacious shelter he’d erected in the Zone in mid-2022. A row of three solar panels outside powered a small air conditioner and an ancient computer. It seemed fitting that the 40-something Burress wore a T-shirt reading, “Green Jobs and Care Jobs Now!”

Soon after that conversation, I walked by a man smoking something from a glass pipe.

When I met with Monica Rico, medical coordinator for Circle the City, she said what I’d seen could have been “blues,” the street name for fentanyl — a synthetic opioid that costs between one and four dollars for 2 milligrams. That small amount, barely enough to cover Lincoln’s beard on a penny, can be fatal, especially when combined with heat stress.

This combination of drugs like fentanyl and heat severely injures residents of the Zone in yet another way, Dr. Bueno said. “People using drugs often pass out in the sun and get severe burns from contact with hot pavement,” he said.

In the summer, Phoenix streets can reach temperatures that are hard to fathom. All the streets in the Zone are paved with black asphalt, which absorbs sunlight and retains heat. On days like July 4, asphalt streets can reach 180 degrees or more. At those temperatures, skin contact lasting a single second can cause third-degree burns.

If the victim lies unconscious on the searing asphalt for too long, Bueno said, the damage can be permanent. When combined with dehydration, as often happens, the injuries are sometimes fatal.

‘They don’t have enough beds’

Gregory, an unsheltered veteran I talked with in the Zone who declined to give his last name, was able to state the immediate problem facing Phoenix and other cities with growing homeless populations: “They don’t have enough beds to house all the people who are homeless, man.”

A survey conducted in January estimated that there were nearly 7,000 people considered homeless in Phoenix and, according to the city, there are just 3,219 beds available for them.

“Our shelters are typically at capacity,” said Rachel Milne, director of the Phoenix Office of Homeless Solutions. “We added 592 shelter beds last year, and we’ll open 462 more this year.” In the meantime, her office was working with other city departments and partnering with community groups to keep people safe as a worst-in-history heat wave rolled into the region.

Today the area’s homeless population is 72% higher than in 2017. If the number of unhoused people continues to grow, the need for beds will continue to outstrip the city’s ability to provide shelter.

“Right now we’re hyper-focused on targeting the most vulnerable of the unsheltered population,” Milne said, opening new heat relief sites, shade tents, and providing water. “When it’s 110 degrees, it’s just not safe for anyone to be outside.”

Phoenix Vice Mayor Yassamin Ansari agrees. “The heat here is absolutely deadly,” she said.

Since 2021, Ansari has served on the Phoenix City Council, representing a district that includes the Zone. She’s widely recognized as a vocal and effective advocate for temporary measures to protect unhoused folks from the summer heat, as well as for policy change to address the root causes of homelessness — including a historic lack of affordable housing.

Tackling the affordable housing shortage

Despite the heat, Maricopa County, which includes the Phoenix metro area, was the fastest-growing county in the U.S. in 2022. So far, affordable housing is not keeping up with the influx.

“Ultimately,” Ansari explained, “this is a housing issue. We are 163,000 housing units short in the city of Phoenix,” she said. “We tout our growth as a positive, which it is in many ways, but we have not been able to keep up with demand for housing, and that’s made the city much less affordable.”

The long and continuing history of housing discrimination in Arizona, and the nation as a whole, plays a significant role in the demographics of homelessness in the city. A 2021 study found that Black residents in the Phoenix metro area are homeless at a rate nearly four times greater than their share of the population, while the homeless rate of Indigenous residents is twice as high. Black residents are also homeless longer than their white counterparts and are more likely to be unsheltered.

Ansari has worked on a number of fronts to make more low- and moderately-priced housing options available in Phoenix. These include a change to zoning regulations to allow duplexes and triplexes in areas now zoned for single-family homes only.

I asked her about what Shy, the woman I’d interviewed on my first visit to the Zone, had told me about being on a waiting list for subsidized housing for three years. Could that be true?

“Unfortunately,” Ansari replied, “it’s not unusual. Some residents have been waiting since 2017. Currently, we have over 16,000 people wait-listed.”

To move people off the dangerously hot Phoenix streets, another of Ansari’s missions is to get Congress to shake loose the number of housing vouchers the city receives from the Department of Housing and Urban Development.

“Of the top ten largest cities in the country,” she recently wrote members of Arizona’s Congressional delegation, “Phoenix receives the lowest allocation of [federal housing] vouchers.” Despite the fact that Phoenix recently surpassed Philadelphia to become the fifth-largest city in the country, she added, Philadelphia receives three times more federal housing vouchers than Phoenix.

Finding shelter in an era of extreme heat

After talking with Ansari, I tried to contact Shy again. But her tent was gone, along with all the others that had surrounded it. Complying with a court order, the city had begun clearing the Zone, one block at a time.

According to Rachel Milne, the director of the city’s Office of Homeless Solutions, 37 of the 44 people displaced on the day Shy’s block had been cleared had accepted an offer of emergency housing. Later, a community aid worker in the Zone wrote that Shy had accepted a place at the Washington Street Shelter.

That was good news. The shelter is a 200-bed facility that opened in 2022, providing wraparound services including meals, access to medical care, classes in yoga, resume-building, and other activities designed to help transition to permanent housing.

I drove to the shelter to see Shy, who was still officially homeless but no longer “unsheltered” in the immense heat. Washington Street Shelter is a secure facility, meaning there were guards checking IDs to ensure that only residents and workers could enter. I told him who I was, showed my ID, and gave him Shy’s full name.

He disappeared into the building only to reappear a minute or two later. Shy was no longer a resident, he said. He confirmed that she had been there but had left. I asked where she had gone. He politely explained that because of client confidentiality, he couldn’t tell me anything more.

I had heard that people sometimes move between shelters, or leave to stay with friends, or check out and return to the streets. I drove back to the Zone and walked around for about an hour, unsure of whether I really wanted to find Shy there. It was 110 degrees and if she had indeed returned to the Zone, that was not a good thing.

But I didn’t see her that day, or since. And regardless, there were still thousands of people just like Shy, struggling to survive unsheltered not only in the Phoenix heat but in cities across the country and all over our rapidly warming planet.

This story was funded in part by a grant from the Institute for Journalism and Natural Resources.