The rise in heat waves caused by climate change is bad for the environment and your electric bill. The increasing intensity and frequency of high-heat days can also stress your body and cause health issues.
Heat waves are associated with increased emergency department visits and hospital admissions. In high-income countries, heat is one of the largest weather-related causes of death, and experts expect heat-related illness, disease and death to continue to rise as climate change progresses.
The good news is that you can keep yourself and your family safe by monitoring the temperature and being prepared. Educating yourself about the effects of heat and how to protect yourself is a good place to start.
Here’s what you need to know:
How heat waves can affect your health
The human body functions best at a certain core temperature — typically between 97 and 99 degrees Fahrenheit — and has processes in place to regulate that temperature (thermoregulation).
During a heat wave, extreme heat can threaten your body’s ability to maintain its core temperature. When that happens, temperature-sensitive nerve cells in your body send up a red flag. The brain responds by:
- Redistributing blood flow closer to the skin to improve the transfer of heat from your muscles to your skin and ultimately out to the environment
- Secreting sweat that evaporates off the skin and removes body heat
How your body handles heat stress and whether it responds appropriately is highly individual. Heat waves can be especially risky for certain populations, such as:
- Adults older than age 65
- People with cardiopulmonary issues and other chronic diseases
- People working outside
- Pregnant people
- Very young children, especially if they have respiratory conditions
Common health impacts of heat include:
1. Dehydration
You can become dehydrated when you sweat a lot and don’t replenish those fluids fast enough. If you are active during a heat wave, dehydration can come on suddenly.
Early signs of dehydration include dry mouth, thirst and dizziness. But if left untreated, dehydration can put your major organs at risk. Dehydration decreases your blood volume, which can put added strain on your heart. It can also affect your kidneys’ ability to process waste.
2. Cardiac stress and failure
Your body’s reaction to high heat demands a lot of your heart. As your body’s demand for oxygen increases, your heart must pump harder and faster. The strain is especially dangerous for people with preexisting heart conditions.
Cardiovascular illness is the primary cause of death during heat waves. Older adults die from heat-related cardiovascular events more than all other heat-related causes of death combined.
3. Mental health issues
Heat waves can also have psychological consequences. Some neurotransmitters that regulate your mood — norepinephrine, dopamine and serotonin — are also involved in thermoregulation.
According to the American Psychological Association, mental health visits to the emergency room more than double on hot days compared to cooler days. Heat waves can worsen many mental health issues, including:
- Anxiety and stress
- Childhood behavioral disorders
- Mood disorders
- Schizophrenia and related disorders
- Self-harm
- Substance use disorders
People who take medication for a mental health issue are especially at risk. Most psychotropic medications, which include antidepressants, anti-anxiety drugs, stimulants and mood stabilizers, can make it harder for your body to handle heat.
4. Heat exhaustion and heat stroke
If your body becomes so stressed that it cannot regulate its temperature, you may begin to overheat. The first signs of heat exhaustion include:
- Headaches and dizziness
- Muscle cramping and weakness
- Shortness of breath
- Unusual sweating
Heat exhaustion can quickly become heat stroke if left untreated. High internal temperatures, heart stress and increased oxidative stress can eventually damage your cells, tissues and organs. Heat stroke is life-threatening.
5. Respiratory distress
Breathing in hot and humid air can worsen breathing conditions, such as asthma or chronic obstructive pulmonary disease (COPD). Respiratory disease is the second leading cause of mortality and morbidity during heat waves (after cardiovascular disease).
High heat can also worsen air pollution. Over time, increased ozone pollution can damage your lungs. Heat-related pulmonary stress and elevated air pollution are especially dangerous for people with preexisting respiratory conditions.
Protect your health during a heat wave
Knowing when a heat wave is expected is critical. It allows you to plan and take precautions early.
The World Health Organization recommends taking these steps to stay healthy in the heat:
- Cool down your home: During the day, block the hot sun with window coverings and turn off unnecessary electrical devices. Use fans if the temperature is below 104 F. Using a fan at higher temperatures can heat your body. If it’s cooler outside than inside your house at night, open the windows to release heat.
- Keep your body cool: Use light and loose clothing and bedding during a heat wave. Take cool showers or baths. Wet your skin with a damp cloth, spray or wet clothing.
- Hydrate: Drink one cup of water per hour to stay hydrated in high heat. Limit beverages high in sugar, sodium, caffeine and alcohol. You are hydrated if your urine color is light yellow or clear.
- Stay out of the heat: Spend time in a cool place, especially during the hottest time of day. Shade can bring temperatures down by 10 to 15 degrees. If there’s a power outage or you don’t have air conditioning, find an air-conditioned public place to stay cool.
Everyone’s reaction to intense heat is different. Your provider can assess your risk and make personalized recommendations to help you stay safe.
