When to Go Inside When It’s Very Hot? It Depends on Your Age

How long you should be out in the heat depends partly on your age.

A prolonged heat wave is forcing a rethink of outdoor safety. Being outside reduces the risk of Covid transmission, and nature has a host of benefits for mental health. But when temperatures soar, people need to balance those positives against heat-related health risks, doctors say. 

People at either end of the age spectrum—kids under 4 and adults over the age of 65—are at the highest risk of heat-related illnesses, including heat exhaustion and heat stroke, because they can’t regulate their core body temperature as efficiently, doctors say. A person’s risk depends on many factors, like medical conditions, acclimation to heat, and medications, so doctors are reluctant to give blanket guidance. 

Anyone experiencing symptoms of heat-related illness should seek medical attention if efforts to cool down, such as by moving into an air-conditioned space, drinking water, shedding clothing or sprinkling cool water onto the body, don’t improve symptoms within a half-hour, doctors say.

Here’s how to assess heat risk by age.  

Young kids

Babies and children under 4 years old are at high risk when it’s hot. 

Just because you’re not overheating doesn’t mean they aren’t: Children’s bodies heat up more quickly than adults’ and have a harder time dissipating heat because they don’t sweat as efficiently, pediatricians say.

Young children are also at greater risk of overheating because they can’t take off clothes to cool themselves down or communicate their discomfort to adults. 

Parents should look for signs of dehydration or heat stress on hot days, including if a young child is crying with no tears, goes a longer time than usual without a wet diaper or has a dry mouth or tongue, says Dr. Tochi Iroku-Malize, a family physician in Long Island, N.Y., and president of the American Academy of Family Physicians.

Check the heat index, which is a measure of the combined feel of air temperature and humidity, and follow local weather advisories to determine whether to cancel or go ahead with outdoor activities with young kids.

Babies younger than 6 months old should be kept out of direct sunlight altogether, the American Academy of Pediatrics advises. 

Older kids 

Kids over 4 have better-developed heat-regulating functions than toddlers and babies. They can communicate more effectively, but they are also more likely to overexert themselves while playing games or sports. 

Once the heat index tops 80, kids who are running around and are visibly flushed or starting to slow down should stop to have some water every 15 to 20 minutes, Iroku-Malize suggests. 

Kids who have been away from school sports over the summer break should ease back into practices and wear loosefitting, light clothing rather than heavy gear, says Dr.

When the heat index exceeds 90 degrees, kids should take breaks at least every half-hour or so from outdoor activities and drink frequently—even if it’s a sports drink or ice pop, says Dr. Karen Goodman, pediatric emergency medicine physician at Hassenfeld Children’s Hospital at NYU Langone. Avoid caffeinated beverages like sodas or energy drinks. 

Parents should check with camp directors, coaches and other caregivers about heat plans in place, including whether they have access to sprinklers, pools or air-conditioned spaces.  

If your child takes certain medications, like antihistamines and some stimulants to treat ADHD, be aware they can raise the risk of heat-related illnesses. Conditions like asthma can increase kids’ heat risks, so parents should check in with their pediatricians during heat waves.

Adults

Healthy young and middle-aged adults are at the least risk for heat-related illness, doctors say. However, they also may be more likely to ignore heat advisories, as well as consume dehydrating caffeinated and alcoholic drinks. 

“I know you want that iced coffee but that’s not going to help you in these situations,” says the AAFP’s Iroku-Malize. Drink water instead.

Pay attention to the heat index, even if you don’t have kids, rather than what the thermometer alone reads, Iroku-Malize says. 

Signs of heat-related illness include heavy sweating, weakness or lightheadedness, nausea or vomiting, a racing heart and confusion. 

Older adults

Adults over 65 are in the highest risk groups for heat-related illness along with babies and young kids, doctors say. 

As we age, it becomes more difficult to stay hydrated. Water volume in the body decreases, urinary issues can drive a desire to drink less to avoid frequent trips to the bathroom, and thirst receptors stop functioning as efficiently, says Dr. Kevin Shih, a geriatric medicine specialist at WellMed at McDermott in Plano, Texas.

Older adults are also more likely to be taking multiple medications and have more chronic conditions, which can further heighten their risks. Sweat glands become less active with age, too. 

Lonnie Steckler, who runs The Pointe of North Gables, an assisted living community in Miami, says staff are being more conscious about encouraging residents to drink water amid a heat wave in the city. Staff at the facility recently hosted the first in a planned series of “Popsicle parties” in the hottest part of the day.

Doctors advise caregivers for older adults to make in-person visits on particularly hot days and keep an eye out for changes in their behavior, such as eating or talking less, that could indicate heat stress, says Shih. Older adults often skip past the early signs of heat-related illness in the general population, such as rash and cramping.

“They may go straight to a little bit of confusion or delirium, and that’s definitely a sign that you should act quickly,” says Shih. 

Write to Alex Janin at [email protected]