As the holiday weekend approaches, large swaths of the Midwest and the Eastern U.S. are under extreme heat warnings or heat advisories, according to the .
Heat is a serious health threat. Hundreds of people in the U.S. each year. Heatstroke can , leading to multiple organ failure or kidney failure, and it can trigger a heart attack.
If you plan to spend time outdoors this week, here's a roundup of advice from NPR reporting on how to protect yourself and your loved ones.
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1. Assess the heat risk before you go outside
There's not an absolute temperature at which extreme heat turns dangerous. Rather, it depends on your individual circumstances, how acclimated to heat you are and how long you're exposed to the heat, a professor of environmental physiology at the University of Roehampton in the U.K.,
Humidity is also a key factor, he says. Sweating works better to cool you off in dry heat than in humidity. Wind flow can also affect the risk of overheating.
"If it's a very humid day and there's no wind speed, then you are more at risk, even if the air temperature is lower," , director of Duke University's Heat Policy Innovation Hub, .
Keep an eye out for heat advisories or warnings in your area issued by the National Weather Service. These typically take into account the local heat index, which includes humidity as well as the air temperature, to get a more accurate read on how hot it will feel outside.
But they are not foolproof, says Nick Staub, incident commander for extreme heat response in Maricopa County, Ariz. "We see a significant number of heat-related deaths on days that are not an extreme heat warning," Staub said,
One reason for this is that the are calibrated for shady locations with light wind. If you're in direct sunlight, it can be 15 degrees hotter than in the shade.
Instead of relying on heat indices alone, check the National Weather Service's tool, which takes several factors into account, including: how far above normal the current temperature is for your location and time of year; heat duration; and humidity forecasts.
2. Know if you're high risk
Some people are at higher risk for heat-related illness, as , and they need to take extra care to stay cool.
This includes people who aren't because they are from cooler regions or spend little time outdoors. and small children can be particularly at risk, partly because of their small body size. Kids also might not notice how they're feeling, or not communicate it clearly, so it's important to that might suggest they're overheating.
People in may have a reduced ability to sweat and thus cool off. bodies also may not cool off well, and heat can raise the risk of pregnancy-related health problems. People with certain or on certain medications may have trouble too.
And finally, outdoor workers or others who do strenuous outdoor activity and those without access to air conditioning are at high risk.
3. Check prescriptions 鈥� heat and some medicines don't mix
Certain medications can make people more vulnerable to heat. For instance, , which millions of people take, are diuretic. "Those medications are trying to get rid of fluid from your body," Wafi Momin, a cardiologist at Memorial Hermann Health System in Katy, Texas, . And if you then add heat, "that can cause a very dangerous situation" of dehydration.
Other types of medications can impair your body's ability to cool off, including (a category that includes Benadryl) and stimulants, like ADHD drugs. ACE inhibitors, commonly prescribed for heart issues, make it harder to notice you're thirsty, and beta blockers 鈥� another heart medication 鈥� can decrease sweating.
"When you're taking these medications and you're exposed to heat, it's like asking a car to drive up a mountain in the summer with the air conditioner broken," David Eisenman, a physician and researcher at the University of California, Los Angeles, "Overheating becomes much more likely."
Psychiatric medications can also interfere with your body's thermoregulation. Antipsychotics and some antidepressants can reduce how much you sweat.
Sedative medications like benzodiazepines may "reduce alertness and perception of heat, says Dr. Ashwini Nadkarni, a psychiatrist and medical director of Brigham General Adult Psychiatry at Mass General Brigham in Boston.
Patients should still take their prescribed medications, Eisenman stresses. But he urges them to take heat risks seriously and make a plan to keep cool.
Ask your doctor whether any of your medicines could increase your risk of heat-related illness. And you can explore a that contribute to heat sensitivity from the Centers for Disease Control and Prevention.
4. Know the difference between heat exhaustion and heat stroke and when to seek emergency care
The include fatigue, extreme thirst, nausea, headache, shortness of breath, rapid breathing, muscle cramping and feeling dizzy or lightheaded.
is a much more serious emergency. The warning signs include all the above but also may include a strong, rapid heartbeat, confusion, vomiting, seizures, slurred speech, or passing out. Watch for a body temperature that exceeds 103 degrees F.
The first step to help anyone who exhibits symptoms of heat exhaustion or heatstroke is to get them to immediately stop what they are doing and rest somewhere out of the sun, , attending emergency physician at Suburban Hospital, Johns Hopkins School of Medicine,.
Take steps immediately to cool the person who's overheated: Get them into air conditioning if possible, or at least shade with a fan or breeze. Mist them with a spray bottle, for example, or pour water over their head. The most important places to cool are the head and face, the armpits and the groin, he says.
If symptoms point to heatstroke (watch especially for neurological symptoms like confusion), get them to an emergency room right away.
5. Keep cool: Avoid midday sun and choose protective clothing
One of the simplest ways to keep your body temperature at a reasonable level on a hot summer day is to only go outside in the morning or evening when it's cooler. And stay in the shade, especially if you're doing anything active.
"That midday sun can add as much as 20 degrees or more to the actual air temperature," , professor of movement science at Columbia University, . "You really have to be careful about that."
And it's important to protect your skin, says Leonard. Your skin is an "amazing self-cooling apparatus," he says. It's designed "to move warm blood away from your core to keep your vital organs cool."
Consider wearing , and include a hat. Leonard recommends wicking athletic fabrics that allow you to sweat.
Choose loose-fitting silhouettes, recommends , assistant professor of emergency medicine at Harvard Medical School. If your clothes are too tight, the sweat on your skin can't evaporate, which is key to keeping your body cool. "I'm sure people don't love sweating profusely, but sweating is actually our friend when it comes to heat," Salas .
6. Prehydrate 鈥� and rehydrate often
If you're outside or in a hot place, dehydration can happen fast. So prepare by hydrating in advance, says Momin, of Memorial Hermann Health System. "Grab a glass of water or a sports drink before you head out to the outdoors," he says.
Bring plenty of water with you, and don't wait until you're thirsty to start drinking during an outdoor activity. "The moment you begin to feel thirsty, you're likely anywhere between 10 to 25% dehydrated already," says, a physician at Houston Methodist Hospital.
Water is the best way to hydrate. Adding electrolytes under normal circumstances. But they can be helpful if you've gotten overheated or you're doing something very physically active and sweating a lot. In that case, it can be a good idea to replace those electrolytes promptly, , an associate professor and director of the Water, Health, and Nutrition Lab at Penn State University, .
7. If you struggle with mental health, take extra care
Higher temperatures are known to have an impact on mental health. Studies show that higher temperatures are linked to for mental health conditions and addiction.
And suicide risk goes up too, a. "We think that every summer roughly an additional hundred young adults are dying by suicide due to increasing temperatures," says study author and psychiatrist at the Hartford HealthCare Institute of Living, who runs the institute's Heat Mind Lab.
If you or someone you know may be struggling with suicidal thoughts, contact the by calling or texting 988.
So, what can people with mental health conditions do to protect themselves from excessive heat? Avoid exposure to heat as much as you can, says Nadkarni of Mass General Brigham. She advises "staying indoors in cooler places" and making sure to hydrate.
She also recommends people talk to their doctors about what their risks are. There can be added risk for people with substance use disorders 鈥� alcohol and certain drugs are diuretics and can cause dehydration. And people with mental illness are also vulnerable to heat-related illness, says Nadkarni, so it's important to watch out for symptoms and seek medical attention promptly if they develop.
Lean into your social networks during times of high heat, suggests , an environmental health researcher at Harvard University's Chan School of Public Health. "If you have a loved one that you know is prone or vulnerable, make sure that you're checking in with them when there's a heat wave," she says.
Rhitu Chatterjee contributed to this report.
Other reporting was drawn from earlier NPR stories. Contributing reporters include: Allison Aubrey, Alejandra Borunda, Maria Godoy, Pien Huang, Emily Kwong, Suzette Lohmeyer, Christine Ro, and Clare Marie Schneider.
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