How hot is too hot?
From a health perspective, it's complicated.
Phoenix statute sets aspecific temperature that rentals with air conditioning units or evaporative cooling systems have to cool to. But health experts say there's not one safe indoor temperature: the impact of heat on the body can vary dramatically person to person based on factors like age, lifestyle and environment.
Frank LoVecchio, an emergency and public health physician and professor at Arizona State University, said general medical guidance typically recommends keeping indoor temperatures under 85 degrees. But he said the ideal temperature varies based on several factors, including personal preference, the use of medications or other substances and existing health conditions.
"Is there a magic temperature that you can say everyone should have for their AC?" LoVecchio said. "I don't think we can say that."
Homelessness, outdoor work, and access to air conditioning or other cooling can also impact vulnerability to heat. The stakes are high, the physician said.
"People think of heat stroke as just simply dehydration, but it's much more dangerous," LoVecchio said. "Heat stroke is really a failure of the body's ability to regulate temperature. At that point, you're not just replacing fluids, but you're trying to prevent organ damage."
The high risk raises questions about the importance of air conditioning in hot climates, LoVecchio said.
"Is air conditioning a luxury during extreme heat?" LoVecchio asked. "Or is it a medical safety intervention?"
Pope Moseley, a lung and intensive care physician who researches the effects of heat on the human body, echoed LoVecchio's warnings about the severity of heat stroke. He said heat stroke is comparable to septic shock and has a high fatality rate.
But there's a wide range of less severe heat illness, as well as heat-related deaths and illnesses that go unreported, Moseley said. He estimated that roughly 90% of the health effects of heat fly under the radar.
Heat has an impact on existing health conditions: When temperatures rise, Moseley said, so do heart attacks, bloodstream infections and problems with emphysema. Mental health can be impacted too. Moseley said heat is correlated with increased hospital admissions for schizophrenia, dementia and psychosis, as well as suicide.
"Heat is the great force multiplier of our illnesses," Moseley said.
Health-based heat guidelines are "OK, Moseley said, but the ASU research professor said heat impacts vary dramatically based on the environment and the individual.
"What we often find is some of those acceptable limits are really in an idealized person, not in an everyday person," Moseley said.
Age is often cited as a risk factor for heat illness. But Moseley said there can be variation within the same age group: An active 70-year-old who hikes every day may have a different heat tolerance than a 70-year-old with heart failure, lung disease and diabetes.
Similarly, someone living in a well-ventilated house with the AC set at 82 degrees, wearing light clothing and running several fans, is in a different situation than someone wearing heavy clothing in a poorly-ventilated building cooled to the same temperature.
"Those are different people," Moseley said.
Alaina Mencinger covers tech, energy and utilities for The Arizona Republic. Reach her at Alaina.Mencinger@usatodayco.com.
This article originally appeared on Arizona Republic: How hot is too hot? Experts weigh in on heat, housing and health
