The Arizona heat is killing people. Just how many? That’s in dispute
Lily Altavena
Every summer in Maricopa County, dozens of autopsy reports are filed, each telling a different story with the same ending. The Korean War veteran who quietly died in his home after the air conditioner failed. The homeless man — a father of three — found in an alley after a hot week. The 5-month-old infant, left too long in a hot car.
Last year, the Maricopa County Department of Public Health counted 130 heat-associated deaths. This year, the department has confirmed five cases, with 57 more under investigation.
Heat kills. And the risk of heat death to Phoenix-area residents could grow if climate scientists are right in their warnings about rising temperatures and a longer hot season. That risk is higher for particularly vulnerable populations, like those who are elderly or homeless. Officials say knowledge is key to putting fewer people in peril.
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How many people die in Arizona from heat every year?
That depends on who you ask.
- According to Centers for Disease Control and Prevention calculations, 46 people died from heat in Arizona out of 335 nationally in 2015, the most recent year available.
- The Arizona Department of Health Services places total heat-related fatalities in the state that year at 83.
- The Maricopa County Department of Public Health reports that 85 people perished in 2015 due to heat-associated causes in just this county.
- On the other end of the spectrum, the National Weather Service attributes just two deaths in the state in 2015 to extreme heat.
Mash that data together and you might conclude that Maricopa County accounts for 25 percent of all heat-related deaths in the U.S. Or 4 percent, if you’re relying on the National Weather Service.
It’s more likely, experts said, that every department collects and tabulates its data differently, leading to a vast range of numbers and an uneven characterization of heat’s deadly impact on the state.
Trying to spot the heat deaths
Tracing those numbers begins at the time of death.
“Part of the uncertainty in the beginning might have to do with how the physician documents the death,” said Will Humble, the executive director of the Arizona Public Health Association.
Accurately tracking the deaths, and emergency-room admissions, is key in developing prevention programs.
“We want to just generally have a better characterization of the burden so that we can do better,” said Jaime Madrigano, an associate policy researcher at the RAND Corporation, a global think tank. “Trying to look at who are the most vulnerable populations during heat waves. Those are the populations we want to target in terms of outreach.”
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Unlike easily-identifiable illnesses, death from heat can be harder to spot.
In some cases, Madrigano said it’s onerous for investigators to gather evidence to substantiate a heat death.
Some repercussions of a major heat wave may ultimately fall through the cracks.
“I think we can be pretty confident that when we just look at those official heat-related deaths, we are likely underestimating the sort of excess burden due to the heat wave,” she said.
Different counting methods
The CDC uses information from death certificates to inform its heat-death numbers, using two codes from the International Classification of Diseases (ICD): deaths attributed to exposure to excessive natural heat and deaths attributed to heatstroke or sunstroke, an agency spokesman said in an email.
The CDC’s process is not unlike the method the Arizona Department of Health Services used in a March 2017 report tracking heat-related mortality, using ICD codes. In all, the department tracked 1,272 deaths from 2005 to 2015.
And where larger counties like Maricopa may have more resources to investigate heat deaths in medical examiner’s offices, smaller counties may end up with a less accurate count.
“You have a very limited pool of medical examiners that may not be able to get there as quickly,” Benjamin Palmer, a spokesman for the Arizona Department of Health Services, said. “They just don’t have the resources. ... Reporting deaths takes some time.”
Maricopa County’s approach
With temperatures rising every year and a growing population, Phoenix is central to studying heat’s deadly impacts. The Maricopa County Department of Public Health actively monitors heat-associated deaths and hospital admissions during the hot season.
“Other health departments look toward Maricopa County as the model,” said David Hondula, a senior sustainability scientist at Arizona State University’s sustainability school.
The department updates the number of confirmed heat-associated deaths and those under investigation in a report on a weekly basis. Epidemiologists track whether those deaths occurred indoors, outdoors, and whether the deceased had working air conditioning.
“Understanding that heat poses as much if not more risk than extreme cold has been something I think that’s been nationally changing,” Kate Goodin, a department epidemiologist, said. “It’s starting to get more attention at a national level.”
Unlike other agencies, the county department works directly with the medical examiner to actively investigate possible heat-related deaths. Reports split the deaths into two categories: heat-caused and heat-related.
This year, five people have died from heat in Maricopa County, while 57 cases are still under investigation. Nearly 30 deaths under investigation occurred in the last week of June; officials said the late June spike is not abnormal compared with other years.
Jeanene Fowler, a spokeswoman for the department, also cautioned against making any conclusions based off the number of suspected cases.
“It’s important to note that on average, 50 percent of those under investigation will be ruled out as heat deaths,” she wrote in an email.
'We need to agree on the data'
The National Weather Service does offer heat-death numbers, but the agency usually reports far fewer deaths than the CDC, the state or the county. While 130 people died from heat-associated causes last year in Maricopa County, according to the county’s department of public health, the National Weather Service’s report lists nine dead in the state and 94 in the country in 2016.
The agency’s process often begins anecdotally in local offices, said Kenneth James, a meteorologist at the National Weather Service headquarters in Silver Spring, Maryland. That means a meteorologist could spot a news article about a suspected heat death and follow up to confirm it. James also said the agency is looking at a narrower range of heat deaths: those suffered during periods of excessive heat.
Paul Iñiguez, a Weather Service meteorologist in Phoenix, said it’s difficult for the office to track a weather-related death if it’s not confirmed rapidly.
“If the impact from weather doesn’t happen basically here and now, it’s hard to track that information,” he said, adding, “We’re not health experts, we’re weather experts.”
Heat deaths sometimes take months — even years — to confirm: 27 cases from last year in Maricopa County are still pending a final cause of death, according to the most recent yearly report from the department of public health.
But the National Weather Service does acknowledge that reporting correct numbers is critical in shaping policy.
“We need to agree on the data,” James said. “Otherwise, we’re going to be disagreeing on the very foundation of our conclusions.”
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the azcentral and Arizona Republic environmental reporting team at OurGrandAZ on Facebook, Twitter and Instagram.
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