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When it comes to examining health risks associated with extreme heat, Phoenix is ground zero.

That’s the conclusion of , a research professor in Arizona State University’s .

For more than 30 years, Moseley, a lung and intensive care physician, has led National Institutes of Health-funded research groups focused on heat-related illness.

He said Phoenix, with its urban heat islands and sustained high summer temperatures, is “the best natural laboratory that exists anywhere.”

“What urbanization has done in Phoenix, its rise of high low temperatures, outstrips any city that we’ve ever looked at,” Moseley said. “This is a major metropolitan area with a massive rise in the temperature markers that determine human illness.”

Moseley and , a professor in the College of Health Solutions, are conducting research using hospital and population data to make the public aware that more people are impacted by heat than those suffering common heat-related illnesses such as heatstroke.

They plan to publish a paper on their research and, hopefully, develop an app that will help people better understand their health vulnerabilities during extreme heat periods.

Pope Moseley

ASU Â鶹´«Ã½ talked to Moseley about the research.

Question: What is the current research you and Marisa are doing?

Answer: By looking at population data and seeing which groups of chronic conditions or diagnoses seek medical help, we can figure out heat vulnerability related to the diagnoses people already have. Most of the people who go to the hospital during a heat wave do not go because of heatstroke or heat illness. That’s less than 10% of the illnesses.

For example, bloodstream infections go way up in a heat wave. Suicides go up 1–2%. Hospitalization for dementia goes way up. Hospitalization for heart attacks goes up. As temperatures go up, drug overdose deaths go up. So, If you tell me 200 people got sick, I’m going to say, “No, 2,000 people got sick. We just didn’t recognize it.”

Data from population studies in Sweden have shown that for every heat wave day, you have an 8–12% increase in overall mortality. Heat is a real force multiplier of the illnesses and chronic conditions that we have. Our job in the College of Health Solutions is to put together the data to allow policymakers to plan and manage what’s going to happen during a heat wave.

Q: What you’re saying is there are far more people vulnerable to heat-related illnesses than might be commonly thought of?

A: Yes. My prior research group at the University of Copenhagen published extensively on the use of population data to understand how diagnoses or chronic conditions relate to each other and can help predict the likelihood of an outcome from a new illness. If, for example, we have a power interruption during a heat wave, we need to know which kinds of medical conditions will need medical help.

A lot of people are likely going to need medical help in that situation, and it’s important to know what medical conditions are most vulnerable.

It’s very different if we’re going to have 100,000 people with emphysema or 100,000 people with kidney failure. We need to be able to have the systems ready to deal with that and actually try to help individuals figure out what their risk is.

Q: What do you consider a heat event?

A: So, a lot of the heat event data was built out of what was important to keep military recruits from getting sick. That has no bearing on a 70-year-old with heart failure and a couple of heart attacks. We are also working with climate scientists trying to look at disease occurrence during the year and use that information to build models of climate conditions associated with illness. For heat, it’s not necessarily how hot it gets, it’s how long it’s hot.

If you go to Death Valley right now, the lows are probably going to be in the mid-80s. If you’re in Phoenix for the next 10 days, our low temperatures are going to be around 90. If you ask me, as an intensive care physician, which one scares me more, it’s Phoenix. There is pretty good population data from the European heat waves in 2003 showing that it wasn’t the high temperatures, but how long it was hot. That means that the area never cooled, as we see in Phoenix right now.

Q: What’s the goal of your research and how might you apply it to help people understand their vulnerability during a heat event?

A: The goal is to provide some sort of actionable knowledge and put together a model of the high-risk person. It’s the same approach we take in cancer therapy. We want to know individual risk of being outside in the heat.

When you do a group study and the results say that the average was a 10% increase in some factor, well, that’s a 10% increase in an average person. There are no average people. If you’re a cancer patient and the doctor tells you, “Well, the average patient has a certain outcome,” you don’t care. That means nothing to you. You want to know the likely outcome for you as an individual. You want to know how heat will affect you, not some mythical average person. That’s the precision medicine of heat.

Q: So, how would you disseminate that information to people?

A: Where we’d like to go is to create a climate app. You input your own health data into your app, and it could tell you your risk of being outside for an extended period of time; your risk of going to the hospital is this; this is your percentage of risk of dying. We should be able to do this for any individual. So somebody with a certain set of chronic conditions knows that when it gets to a certain temperature, they’re more susceptible. That’s where we need to go with this research.

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Hot weather can worsen underlying health conditions, ASU expert says.

A system of personalized medicine could be one way to identify and possibly treat the people who are most at risk for heat-related death, according to a professor at Arizona State University.

“When we focus on heat-related illnesses, we’re likely only seeing a small fraction of what impacts us during heat events,” said , a research professor in the College of Health Solutions and an intensive care physician.

“That’s because heat worsens many health conditions. We can use those co-morbidities to model who is most vulnerable during heat.”

Moseley spoke during a webinar on Thursday that was part of the series from the College of Health Solutions called “Heat and Health: How to Help Vulnerable Populations.”

Pope Moseley

So far in 2022, Maricopa County has 42 confirmed heat-related deaths, Moseley said. But he believes that the true toll is much higher because heat worsens conditions such as asthma, hypertension, diabetes, chronic obstructive pulmonary disease and psychiatric illness, and also can cause medication-related side effects. Even drug-overdose deaths increase during hot weather.

“We need to understand the phenotype of a heat-vulnerable individual,” he said. “We need to help each individual know how heat affects their risk.”

About 65% of the population has at least one health condition that can be impacted by heat, he said.

Artificial intelligence can help. Moseley also is a professor at the University of Oslo, where he works with a research team analyzing large data sets to reveal disease relationships. The team uses artificial intelligence to predict an individual’s chance of surviving a stay in an intensive care unit.

“This strategy can be used to correctly predict anything from the likelihood of a heart attack to the risk of going to the hospital in a heat wave,” he said.

“For the community, we need to plan the same way we do for hurricanes, earthquakes and tornadoes.”

Planning could potentially lead to an app that alerts high-risk people during heat events, and the creation of preventive measures like exercise to build heat acclimation, medication changes or priority status to maintain or restore power.

“There are certain diagnoses and combinations of diagnoses that make one more susceptible to heat,” he said.

“That’s where personalized medicine comes in. We see the issue of substance abuse, but when we add substance abuse to asthma or chronic renal disease, we find the most vulnerable among the vulnerable.”

The webinar also featured , an associate professor in the and the director of heat response and mitigation for the city of Phoenix.

David Hondula

He said that Maricopa County has seen a 454% increase in heat-related deaths over the past several years, from 61 in 2014 to 338 in 2021 — a rate that far outpaces population growth. And the unsheltered population is especially vulnerable, being two to three times at higher risk of heat-associated death.

“ASU was a pioneering institution dating back to the 1990s in understanding that heat is a social justice concern,” he said, noting research from that era showed that the hottest neighborhoods tend to have residents who are lower income and people of color.

“What emerged from ASU research is that there’s been a governance gap regarding heat. Who will implement a personalized heat medicine design? If it’s not clear where the responsibility is, it’s very likely that we will have missed the opportunity to improve health,” he said.

In its 2021–22 budget, the city of Phoenix allocated $2.8 million for the .

“We created the country’s first publicly funded office in local government focused on heat so when there’s confusion over who’s responsible for programming and services that can intervene ahead of these deaths, it’s clear where those conversations start and it’s with our new office,” he said.

“We learned that the city has more than 30 programs related to heat response, and this is the first time we had them all written down in one place.”

The number of unsheltered people has more than doubled in the past year, Hondula said, and part of the city’s initiative is an outreach team called We’re Cool, which visits various locations including places where people live on the streets as well as urban trails. The teams include a case manager.

“So we’re not just giving out water bottles,” he said. “We’re able to have conversations about shelters and services.”

Part of the money in the budget will go toward planting trees in neighborhoods and training neighbors to care for them.

Both Hondula and Moseley said that building more housing is a critical element of decreasing heat-related deaths.

“We have a real health emergency,” Moseley said.