Summer’s searing heat and humidity can not only sap your energy, it can cause a raft of serious potentially fatal health issues.
Steamy weather can not only be enervating, it poses serious health risks for many people, says Dr. Donald Lloyd-Jones, president of the American Heart Association and chair of the department of preventive medicine at Northwestern Medicine in Chicago.
High temperatures and humidity can be dangerous for:
- Older people (particularly individuals age 70 and above).
- People who take heart medication.
- Patients who take medication for high blood pressure.
Medication for cardiovascular disease and high blood pressure could alter their body’s ability to dissipate the effects of heat, Lloyd-Jones says.
While heat and humidity pose a greater risk for older people and individuals taking medications for certain conditions, it’s important to keep in mind that soaring temperatures can also be harmful to younger, healthy people if they don’t take precautions.
“Heat can affect anyone,” says Dr. Michael Emery, co-director of the Sports Cardiology Center at Cleveland Clinic. As temperature and humidity levels go up, so do the risks. Engaging in physical labor or working out vigorously in hot and humid conditions also boosts the risk.
The Deadly Effects of Heat
On hot, sticky days, your heart needs to pump harder to initiate the sweating response that cools the body. For people who already have a weakened heart, that extra pumping can cause stress on the cardiovascular system. This combination can have deadly consequences.
Annually, hundreds of people in the U.S. die because of heat, according the Centers for Disease Control and Prevention.
Between 2004 and 2018, an average of 702 heat-related deaths occurred in the U.S. annually, according to a CDC report published in 2020. On average, heat is an underlying condition in 415 of these deaths each year and it’s a contributing cause in 287 deaths. “Extreme heat can exacerbate certain chronic medical conditions,” such as hypertension and heart disease, the report says.
Using alcohol or drugs – such as methamphetamine and cocaine – are also risk factors for heat-related deaths. The report found that “exposure to environmental heat was a contributing cause for several alcohol poisoning and drug overdose deaths. A significant increase in mortality risk associated with unintentional cocaine overdose has been reported during periods of extreme heat.”
The report notes that some people whose deaths were attributed to mental and behavioral disorders as the underlying cause of death were listed with codes indicating heat as contributing causes. “In addition to compromising the body’s ability to cope with heat stress, certain psychiatric conditions can alter risk perception and reduce awareness to prevailing hot conditions,” the report says.
By the end of the century, premature deaths related to heat exposure are estimated to rise by 50,000 to 110,000 a year because of climate change, according to a study published in 2020 in Geohealth.
The Elderly and Heat
Older people have less ability to regulate their body temperature. Also, 80% or more of people age 70 or older have high blood pressure. Many are taking medications for the condition, which can blunt the normal responses the body uses to try to cool down.
As people age, their ability to regulate their core temperature can become compromised. Heat exhaustion occurs when a person’s body fails to cool itself.
Symptoms of heat exhaustion include:
If those symptoms progress, they can lead to heat stroke, which means a person’s core temperature rises above 104 degrees, causing complications to the central nervous system. At that point, organs can start to fail. It’s a medical emergency.
When this happens, people feel hot and dry, rather than clammy and weak.
With age, plaque often begins to build up in the arteries, causing them to become more stiff. Plus, the elderly may not feel as thirsty in the heat, and they may not recognize signs they need to hydrate.
During heat exhaustion, blood pressure drops, which can be dangerous because it can cause people to become unsteady and even to fall or faint.
Dehydration, which occurs when the body does not have enough fluid, is one of the main causes of heat exhaustion. This causes blood volume to drop, meaning the heart cannot fill properly and pump blood to the body’s organs. In extreme cases, organs will not have enough blood to function properly.
In very serious cases of dehydration, a person would need to get fluids intravenously. Mild dehydration – characterized by thirst and depleted energy – is common and can be reversed by drinking fluids. “In 95, 100 degree heat, we all lose more fluid,” says Dr. Malissa J. Wood, co-director of the Corrigan Women’s Heart Health Program at Massachusetts General Hospital Heart Center and an associate professor of medicine at Harvard Medical School. “People don’t recognize they are losing fluid through breathing, even if they’re just sitting by the pool. Your breath has droplets of fluid. The air takes away fluid from the skin.”
With outdoor exercise, such as bike riding or gardening, people lose large amounts of fluid fast. “If you exercise, you’ll lose an excessive amount of volume,” Wood says. “If you’re exercising over 30 minutes, take water with you. Drink water, or water with electrolytes.”
It’s important to replenish sodium, potassium, magnesium and other electrolytes to maintain healthy muscles and organs. Electrolytes aid bodily functions such as regulating your heart beat and helping your muscles contract.
When they’re low, and when the body doesn’t have enough fluid, it becomes taxed. “The cardiovascular system is in more stress,” Wood says. “The heart and blood vessels are in more stress.”
Tips to Stay Heart-Healthy in the Heat
Heart experts recommend these six tips to safeguard your heart in the heat:
- Avoid alcohol and caffeine.
- Dress for the heat.
- Stay inside during peak sun hours.
- Don’t stop taking your medications.
- Acclimatize to the heat.
Hydrate. If you’re going to spent time outdoors in extreme heat, it’s important to drink plenty of water before, during and after. One way to tell if you’re consuming enough fluids is to monitor your urine output. If your urine is pale or colorless, it means you’re getting enough water. But if your urine becomes dark or concentrated, it means your kidneys are trying to hold onto it and you’re not drinking enough fluids, Lloyd-Jones says.
Avoid alcohol and caffeine. It’s best not to consume beverages with alcohol and caffeine on hot days. Such drinks irritate the heart and compromise your body’s ability to regulate its temperature.
Dress for the heat. Lightweight clothes, light colors, breathable fabrics and a hat to shield the sun are all appropriate. Sunscreen will also help reduce the amount of heat you’re absorbing, Lloyd-Jones says.
Stay inside during peak sun hours, 10 a.m. to 4 p.m. Exercise early in the morning or in the evening, and bring a friend for safety. You can also work out indoors on a treadmill or stationary bike.
Don’t stop taking your medications. Check with your health care provider if you start feeling light-headed in the heat. Your health care provider may adjust your medications during the hot weather and will probably advise you to stay hydrated.
Acclimatize to the heat. Start exposing yourself to the heat a little bit at a time, day by day. Spending a bit more time each day in hot weather will help your body adjust to the high heat and humidity.