Despite the dramatic reduction in L.A. drug overdose deaths in the last few years, there’s a fly in the ointment: With 1,894 drug-related deaths over the last decade, July was the decade’s single deadliest month for overdoses in L.A., according to the county health department.
“It’s very likely that a good chunk of those deaths are triggered by extreme heat exposure,” said Bharat Venkat, a UCLA professor and director of the university’s Heat Lab.
There are a few reasons that can happen. “Opioids alter your internal thermometer…. You may not turn on the sweating as fast,” said Dr. Pope Moseley, a lung and critical care physician who has studied the intersection of heat and drug toxicity in Arizona.
Opioids also impair heat exchange through the skin and increase gut permeability, which, under extreme temperatures, can lead to heatstroke, respiratory failure or sepsis.
At the same time, opioids often render users too sedated to move into the shade or seek help, said Dr. José Luis González, medical director of Healthcare in Action, a nonprofit providing services primarily to the unhoused. “If you’re falling asleep, then you’re not able to seek shelter once your body does get overheated.”
Methamphetamine poses a different set of problems, making people erratic or agitated, and more physically active in hot conditions.
In both cases, drug use can impair a person’s ability to respond to environmental heat, either by actively cooling off or recognizing danger.
In theory, public cooling centers should help many — especially the unhoused — avoid the worst effects of increasing heat. But as Moseley and other experts note, many cooling centers probably do not allow in anyone who is obviously on opioids or meth — thus excluding the population most likely to die.
Despite the evidence of heat’s role in exacerbating drug overdoses, officials in L.A. cast doubt on the idea that high temperatures directly cause an increase in overdose deaths. In an email to The Times, a Los Angeles County Department of Public Health spokesperson wrote, “The issue is more about folks being moved indoors during inclement weather and those people using drugs alone, versus in groups, which puts them at higher overdose risk.”
Official data from L.A. County show just 118 heat-related deaths from 2015-2024. But that number is probably a severe undercount, as previous analysis from The Times has shown. Indeed, the health department spokesperson acknowledged that such heat-related deaths are “likely undercounted because heat can exacerbate chronic conditions like heart and respiratory disease but might not be recorded as a factor in a death record.”
Largely, the disparity is due to how the L.A. County medical examiner, who is charged with certifying and investigating all “unnatural and sudden” deaths in the county, categorizes these fatalities.
Effective public health responses depend heavily on accurate death certification, but the U.S. death investigation system is highly fragmented and inconsistent. “There is no one guideline or criteria for certifying heat-related deaths, or in fact, any other kind of death,” said Dr. Christina VandePol, former coroner of Chester County, Pa.
Although VandePol points out that resources exist for medical examiners to consider environmental factors, such as the Centers for Disease Control and Prevention guides on certifying disaster-related deaths, these are mostly advisory rather than binding.
In some parts of the country, that’s changing.
For example, in Arizona, the medical examiner offices in Pima and Maricopa counties have implemented protocols requiring investigators to ask about heat in any deaths occurring between April and October. Systematically documenting environmental heat in this way led Maricopa County to report 645 heat-related deaths in 2023 — compared with just 61 in 2014.
In L.A. County, the approach for attributing heat as a cause or contributing factor to a death is highly discretionary, relying on individual investigators and medical examiners even considering heat as a factor, said Dr. Odey C. Ukpo, the county’s chief medical examiner and coroner.
“Each investigator takes note of the surroundings or circumstances around the death,” Ukpo said. Heat-related deaths are often “a diagnosis of exclusion,” according to Upko, meaning that only after ruling out all other causes, can an L.A. County investigator cite heat as the reason for a death.
Then there’s the question of how L.A. decides what counts as an “overdose.”
Ukpo said his office doesn’t use that term — and instead says “drug-related death,” as people can die even when using small amounts.
Determining whether a death is “drug-related” involves examining the body, ruling out injury or natural disease as causes and performing toxicology reports. Contrary to popular belief, “we don’t look at it and have a certain threshold” about how much a person used, Ukpo said. “It’s more deductive reasoning that nothing else can explain the death. Any level [of a toxin] can kill somebody.”
In cases involving drugs and heat, the decision of whether heat is documented as a contributing factor can vary significantly. “It’s tricky,” Ukpo said.
This approach is not unique to L.A. County, according to Michelle Jordan, vice president of the National Assn. of Medical Examiners, who said many medical examiners across the country follow the same guidelines.
The discretionary nature of this decision-making raises concerns among public health experts about potential underreporting.
The lack of uniform standards across jurisdictions significantly impacts public health responses, VandePol said. “Anytime you’re not counting something, you can’t do anything about it,” she said. “If you don’t know a problem exists, you can’t address the problem.”
The Santa Clara County medical examiner’s data dashboard offers glimpses of how heat- and drug-related factors could both be captured in a death record. It may be imperfect, but it’s probably better than what little L.A. has to offer.
Ukpo expressed openness to enhancing L.A. County’s process, noting recent efforts to integrate epidemiological analysis into death investigations to better understand environmental influences. “We got an epidemiologist for the first time in our department’s history,” Ukpo said. “We are looking at cases, planning heat maps, surveillance and transient trends to better answer these questions.”
Meanwhile, the increased politicization surrounding anything climate-related in the current Trump administration has made the role of heat in drug-overdose deaths “a political football,” VandePol said.
The disparities in how overdose deaths intersect with extreme heat are certified and reported highlight broader systemic issues, reflecting inconsistencies and gaps that may obscure the true effect of climate-related health risks in L.A.
“We need to start recognizing that heat is a killer,” Moseley said.
