Anomalously high and low temperatures affect human habits in myriad ways—forcing us inside, disrupting our sleep, and even exacerbating mental health conditions.
Temperature extremes seem to affect drug use and overdose deaths, too. A new study published in Drug and Alcohol Dependence shows that both extreme heat and extreme cold may cause an uptick in fatal overdoses. The study adds to a limited but growing field of research on temperature and drug use and could help communities better prevent overdoses, especially as climate change makes our weather more volatile.
Fatal overdoses are “something we need to pay attention to in the future” as extreme temperature events affect more people.
Fatal overdoses are “something we need to pay attention to in the future” as extreme temperature events affect more people, said Thanh Lu, a research economist at RTI International, a science and policy research institute, and lead author of the new study. (Although there is significant debate about the role of climate change in the occurrence of extreme cold events, there is scientific consensus that climate change is increasing the frequency and intensity of extreme heat waves.)
Though there is little research in the space, the study confirms previous findings indicating a link between heat and overdoses, said Raminta Daniulaityte, a population health researcher at Arizona State University who was not involved in the new study.
Hot and Cold
To further study the link between extreme temperatures and fatal overdoses, Lu and the research team compared cause-of-death data from 1999 to 2021 from the National Center for Health Statistics to county-level weather data from NOAA’s Global Historical Climatology Network. They analyzed how many fatal overdoses occurred when a person would have been experiencing extreme temperatures relative to a typical day in that county in each month.
They found that annual fatal overdoses increased with temperature extremes. For example, one day above 90°F (32°C) relative to days in the 70°F (21°C) to 80°F (27°C) range led to a 0.2% increase in overdoses. Similarly anomalous extreme low temperatures led to a similar increase in overdoses. According to the analysis, in 2021, temperatures likely drove 1,431 of the year’s 107,000 fatal overdoses.
Despite the link, the overall impact of extreme temperatures on total overdoses was still small, with temperature driving about 1% of the total annual fatal overdoses that the team studied.
Researchers also found that the types, not just the number, of overdoses varied with temperature; opioid-related overdoses occurred more at extreme low temperatures, while stimulant-related overdoses were more correlated with extreme high temperatures. The results align with what Daniulaityte sees in her research in the Phoenix area, where afternoon temperatures in the summer frequently exceed 110°F (43°C). In particular, her research shows a significant relationship between the impacts of heat and overdoses from stimulants, she said.
Extreme temperatures likely drive overdoses in two main ways, Lu said: First, substance use can decrease the body’s ability to cope with extreme heat and extreme cold, making some of the effects of substances, like altered heart rate and weakened breathing, more likely to lead to a fatality. Second, extreme temperatures can affect economic or employment opportunities, decreases in which are known to increase overdoses.
“We were not able to examine or tease out what mechanism, specifically, is a key driver,” Lu said. However, moderately high and low temperatures had a small effect on fatal overdoses, too, indicating that heat and cold can drive overdoses even when it’s not too hot or too cold to go outside or go to work. This means the physiological effects of extreme temperatures likely play an important role, she said.
Daniulaityte said scientists see more consistent links between heat and stimulant-related overdoses than opioid-related overdoses. “We need more data” on how heat affects opioid-related overdoses, she said.
Prevention in a Warming World
The overall impact of extreme temperatures on total overdoses was small in the study, and the researchers did not explicitly link the increase in fatal overdoses to climate change. Still, extreme temperature may become more of a factor in overdose deaths as the climate continues to warm, Lu said.
“People who will be impacted first will be people who experience multiple vulnerabilities.”
Mitigating the effects of extreme temperatures on overdose deaths could look like providing more cooling and warming centers for unhoused people who use drugs or increasing communities’ supplies of naloxone (a medication that reverses an opioid overdose) when extreme temperatures are expected, Lu said. Policymakers should pay equal attention to the effects of both extreme cold and extreme hot weather on overdoses, she said.
Daniulaityte emphasized that increased risk for overdoses is just another way that climate change harms the most vulnerable members of society. “We see the risks [of overdoses] significantly higher for people who are experiencing housing instability and poor access to health services,” she said.
“People who will be impacted first will be people who experience multiple vulnerabilities.”
—Grace van Deelen (@gvd.bsky.social), Staff Writer