Doctors warned of the impacts of extreme heat on physical and mental health, particularly for vulnerable populations, during a online briefing hosted by SciLine last week.
“We know that there are about 30 deaths a year [among] …children left in cars,” said Perry Sheffield, MD, MPH, of the Icahn School of Medicine at Mount Sinai in New York City, warning that cars can be “very hot” even when outside temperatures is less than 70°F.
While these deaths are rare, the much more common heat-related deaths have no warning signs, he noted. “So whether or not heat plays a role, and how it plays a role, is really not quantified.”
Some 11% of emergency department visits to U.S. children’s hospitals in hot seasons were attributed to high temperatures, according to a study Sheffield and colleagues published in Environmental Health Perspectives in January.
Another vulnerable demographic is people with sickle cell disease, who are “exquisitely sensitive” to dehydration, Sheffield said. Under stressful conditions, the walls of your red blood cells change shape, which can cause coagulation or “microcoagulation” that can affect various organs. Even those with sickle cell trait, those who carry just one copy of the gene that causes sickle cell disease, may be more prone to the health effects of heat.
“Up to 3 million people living with sickle cell trait are at increased risk of sudden death during exercise in hot weather,” he added.
Researchers are also beginning to ask questions about the long-term health impacts of heat; for example, the effect of repeated exposures to heat and dehydration on the kidneys. They are also looking at other genetic variations that may increase “heat health risks,” such as muscle contractility.
Extreme heat and mental health
Amruta Nori-Sarma, PhD, of the Boston University School of Public Health, said her research has looked at “the physical and mental health burden” associated with days of extreme heat, which is projected to increase over time. climate change.
She noticed that seven of the warmest years on record in the continental US they have occurred since 2015. The warmest year on record was 2016, followed by 2019 and 2020.
Direct physical effects of heat exposure include heat stroke, heat stress, swelling, and heat rash, while indirect physical effects are often due to underlying conditions, which can lead to cardiovascular disease and kidney failure.
While the physical effects are well researched and documented, the mental health impacts of heat exposure are “poorly understood,” Nori-Sarma said.
She and her colleagues examined the relationship between warm season months (May-September) and mental health-related emergency department visits from 2010 to 2019 in a study published in JAMA Psychiatry in February.
“What we found in this study is that as the temperature increased, the rates of mental health emergency department visits across all mental health causes we’re interested in saw a corresponding increase,” noted Nori- Sarma, which included substance use, anxiety, mood disorders, schizophrenia, and self-harm.
“This tells me that heat is likely to be an external stressor exacerbating existing mental health conditions in people,” he added.
Regarding the pathways that might affect people’s mental health during these periods, “one of the things we could hypothesize would be the disruption of sleep periods that occur because people experience high temperatures, or even discomfort or irritation during sleep.” day,” he said. Another pathway that could affect younger people in particular is stress related to climate change.
Prevention
Nori-Sarma noted that Boston has proposed and is beginning to implement a climate adaptation plan to reduce people’s vulnerability to heat, including building green spaces and leveraging sustainable design to reduce people’s exposure to heat. and extreme cold inside buildings.
Also, one of his doctoral students, Ken Adams, is working on producing a report on the location of cooling centers in 70 different cities.
Nori-Sarma and Sheffield also touched on another vulnerable demographic: outdoor workers who have occupational exposures to extreme heat. One of the ways employers can prevent adverse outcomes for their workers is to provide them with sun protection and encourage them to drink water and rest more often.
Another strategy has been to eliminate work hours that fall during the hottest part of the day, Nori-Sarma said, which would mean starting work earlier in the morning and working a little later at night.
Sheffield noted that the National Institute for Occupational Safety and Health has created a mobile app to educate both workers and employers about the risks of extreme heat, which also sends out alerts on very hot days, as well as advice on safety precautions. .
Hospitals already take advantage of electronic medical records to send alerts to vulnerable patients about approaching hurricanes and high winds as a matter of disaster preparedness, Sheffield noted. Extreme heat could be one more alert they should consider.
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