In 2024, the planet experienced the hottest summer recorded in history.
These record-setting temperatures not only impact the well-being of the environment but have dangerous consequences for the health of human beings, as well.
Extreme heat is among the most fatal weather events in the U.S., typically killing more people annually than hurricanes, tornadoes and floods combined. In 2023, roughly 2,300 people nationally died of heat-related causes, according to death certificate data compiled by the Centers for Disease Control and Prevention. Those most at risk include people who work and live outdoors, have chronic health conditions, or take certain medications.
Robert Dubrow, an epidemiologist and the co-faculty director of Yale’s Center on Climate Change and Health, said heat is likely so fatal because it affects more people than other, more contained natural disasters.
“We’ve been seeing reports during the summer where 150 million people are being exposed to high heat during a given day. That doesn’t happen with hurricanes or floods,” said Dubrow.
Extreme heat can cause illnesses like heat stroke and heat exhaustion, but that’s just the tip of the iceberg. Heat can also exacerbate chronic health conditions, like kidney, cardiovascular and respiratory diseases. Hot weather even has demonstrated effects on mental health, including irritability, impulsivity and trouble concentrating.
“It’s actually much broader than you could even imagine,” said Connecticut Department of Public Health Commissioner Manisha Juthani, of the far-reaching health impacts of extreme heat.
During stretches of hot days this summer, Connecticut’s hospitals saw an uptick in heat-related emergency room admissions. In an average summer week, the state’s ERs admitted roughly 30 people for heat-related illnesses. But, during heat advisories, those numbers more than doubled to as high as 84.
Dubrow explained that both the state’s ER admissions and the CDC’s death toll data undercount the true health impacts of heat because they only include cases directly attributable to heat-related illnesses, like heat stroke.
“If someone died of a heart attack where heat contributed, that would never be captured,” said Dubrow. “We have to develop better methodology to make more accurate estimates of the number of heat-related deaths every year.”
One expert estimated that, in 2023, heat actually killed around 11,000 Americans, nearly five times the official CDC death toll of 2,300. Dubrow also noted that air pollution from wildfire smoke is likely on par with, or even worse than, extreme heat when it comes to deadliest weather phenomena.
Who is most at-risk?
People who cannot avoid the heat, including those who work outdoors and those experiencing unsheltered homelessness, are at high risk to the adverse effects of heat.
Earlier this year, the Occupational Safety and Health Administration, or OSHA, proposed a heat injury and illness prevention standard. Among other measures, it requires paid 15 minute breaks every two hours when the heat index exceeds 90 degrees Fahrenheit. And, based on research that the body can acclimate to heat, OSHA proposed that new and returning workers gradually increase the amount of time spent in hot conditions, including more built-in breaks.
But workers aren’t the only ones who have a more difficult time avoiding extreme temperatures.
Michele Conderino, the executive director of Open Doors, a Norwalk-based homeless service provider, said that the wildfire smoke from Canada last summer fundamentally changed the way Connecticut providers thought about environmental threats to people experiencing homelessness.
“When we’ve talked about extreme weather historically, we’ve talked about winter and cold weather,” said Conderino. “This summer, when our heat spiked, we were very deliberate about going out every single day, multiple times a day.”
For the past few summers, Conderino said, street outreach has included strategies to mitigate the effects of heat waves, like offering people ice cold water and freeze pops, as well as reminding them that they could go to a cooling center to get out of the heat. Conderino added that increased funding for outreach work, partnerships with medical providers and adequate space for people to find shelter could also help people experiencing unsheltered homelessness in periods of extreme weather.
Aside from those prone to more heat exposure, people with chronic illnesses, like cardiovascular, kidney and respiratory diseases are also more at risk. For example, heat may increase the chances of heart attack and heart failure for those with cardiovascular disease. It could also elevate the risk of dehydration for those with kidney disease.
People on certain medications should also use caution. For example, diuretics cause dehydration, antipsychotic medications reduce sweat production, and non-steroidal anti-inflammatory drugs can impair kidney function. These side effects can exacerbate the known effects of extreme heat.
What’s the solution?
Experts admit we have a long way to go in understanding how to keep people healthy during extreme heat.
“There are thousands of people dying from heat in this country every year, and we have a modicum — and that might be generous — of evidence as to what are the best ways to actually keep people safe,” said Aaron Bernstein, co-director of the Center for Climate Health and the Global Environment at Harvard’s School of Public Health, at a conference for health reporters last week.
There is still a lack of evidence-based research on how to protect specific groups, like farm workers or people experiencing homelessness, Bernstein said. And some of the typical solutions to extreme heat have obvious pitfalls. For example, someone without transportation might have to wait in extreme heat for a bus just to get to a cooling center.
While expanding access to air conditioning seems like an obvious solution, it would come with its own set of challenges. Not only is it unaffordable for many, it’s also energy-intensive and produces greenhouse gas emissions, which actually exacerbates the long-term problem of increased heat, said Dubrow. Fans are a cheaper alternative and do provide relief, but cannot prevent heat-related illness once temperatures hit the high 90s.
The CDC recommends people protect themselves by drinking plenty of water and staying inside with air conditioning, if possible, whether that’s at home or in a public space, like a cooling center.
In the long-term, changes to help cool the environment, like planting more trees and installing “green” roofs could help. Public health campaigns are also trying to raise awareness of the health dangers of heat. The Department of Public Health created a toolkit for local health departments to use during heat advisories that includes templates for press releases and social media posts.
Bernstein said he’d like to see clinicians and community organizations partner to provide tailored solutions for individuals and groups who are most at risk.