Climate change is expected to increase the frequency, duration, and intensity of heat waves, affecting public health.

Increased daytime temperatures, reduced nighttime cooling, and higher air pollution levels associated with heat events can affect human health by contributing to:

• Respiratory difficulties
• Heat cramps
• Exhaustion
• Non-fatal heat stroke
• Death

Those most vulnerable to extreme heat are the elderly, very young children, infirm, poor, and socially isolated people, and those who are pregnant are at particular risk during heat waves.

People living in cities are already at a higher risk of heat waves because urban areas are warmer than surrounding non-urban areas due to the heat island effect. This may further compromise the health of vulnerable populations.

Heat related deaths and illnesses are preventable. Despite this, around 618 people in the United States are killed by extreme heat every year. This website provides helpful tips, information, and resources to help you stay safe in the extreme heat this summer.

What is Extreme Heat?

Extreme heat is defined as summertime temperatures that are much hotter and/or humid than average. Because some places are hotter than others, this depends on what’s considered average for a particular location at that time of year. Humid and muggy conditions can make it seem hotter than it really is.

What Causes Heat-Related Illness?

Heat-related illnesses, like heat exhaustion or heat stroke, happen when the body is not able to properly cool itself. While the body normally cools itself by sweating, during extreme heat, this might not be enough. In these cases, a person’s body temperature rises faster than it can cool itself down. This can cause damage to the brain and other vital organs.

Some factors that might increase your risk of developing a heat-related illness include:

• High levels of humidity
• Obesity
• Fever
• Dehydration
• Prescription drug use
• Heart disease
• Mental illness
• Poor circulation
• Sunburn
• Alcohol use

Who is Most at Risk?

Older adults, the very young, and people with mental illness and chronic diseases are at highest risk. However, even young and healthy people can be affected if they participate in strenuous physical activities during hot weather.

Summertime activity, whether on the playing field or the construction site, must be balanced with actions that help the body cool itself to prevent heat-related illness. Use this website to learn more on how to stay safe in the heat this summer, including how to prevent, recognize, and cope with heat-related illness.

What happens to the body as a result of exposure to extreme heat?

People suffer heat-related illness when the body’s temperature control system is overloaded. The body normally cools itself by sweating. But under some conditions, sweating just isn’t enough. In such cases, a person’s body temperature rises rapidly. Very high body temperatures may damage the brain or other vital organs. Several factors affect the body’s ability to cool itself during extremely hot weather. When the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly. Other conditions that can limit the ability to regulate temperature include old age, youth (age 0-4), obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, and prescription drug use and alcohol use.

Who is at greatest risk for heat-related illness?

Those at greatest risk for heat-related illness include infants and children up to four years of age, people 65 years of age and older, people who are overweight, and people who are ill or on certain medications.

What is heat stroke?

Heat stroke is the most serious heat-related illness. It occurs when the body becomes unable to control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided.

What are the warning signs of a heat stroke?

Warning signs of heat stroke vary but may include the following:

• An extremely high body temperature (above 103°F)
• Red, hot, and dry skin (no sweating)
• Rapid, strong pulse
• Throbbing headache
• Dizziness
• Nausea
• Confusion
• Unconsciousness

What should I do if I see someone with any of the warning signs of heat stroke?

If you see any of these signs, you may be dealing with a life-threatening emergency. Have someone call for immediate medical assistance while you begin cooling the victim. Do the following:

• Get the victim to a shady area.
• Cool the victim rapidly, using whatever methods you can. For example, immerse the victim in a tub of cool water; place the person in a cool shower; spray the victim with cool water from a garden hose; sponge the person with cool water; or if the humidity is low, wrap the victim in a cool, wet sheet and fan him or her vigorously.
• Monitor body temperature and continue cooling efforts until the body temperature drops to 101-102°F.
• If emergency medical personnel are delayed, call the hospital emergency room for further instructions.
• Do not give the victim alcohol to drink.
• Get medical assistance as soon as possible.

What is heat exhaustion?

Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. Those most prone to heat exhaustion are elderly people, those with high blood pressure, and those working or exercising in a hot environment.

What are the warning signs of heat exhaustion?

The warning signs of heat exhaustion include the following:

• Heavy sweating
• Paleness
• Muscle cramps
• Tiredness
• Weakness
• Dizziness
• Headache
• Nausea or vomiting
• Fainting

The skin may be cool and moist. The pulse rate will be fast and weak, and breathing will be fast and shallow. If heat exhaustion is untreated, it may progress to heat stroke. See medical attention if symptoms worsen or last longer than one hour.

What steps can be taken to cool the body during heat exhaustion?

• Drink cool, nonalcoholic beverages.
• Rest.
• Take a cool shower, bath, or sponge bath.
• Seek an air-conditioned environment.
• Wear lightweight clothing.

What are heat cramps and who is affected?

Heat cramps are muscle pains or spasms – usually in the abdomen, arms, or legs – that may occur in association with strenuous activity. People who sweat a lot during strenuous activity are prone to heat cramps. This sweating depletes the body’s salt and moisture. The low salt level in the muscles causes painful cramps. Heat cramps may also be a symptom of heat exhaustion. If you have heart problems or are on a low-sodium diet, seek medical attention for heat cramps.

What should I do if I have heat cramps?

If medical attention is not necessary, take the following steps:

• Stop all activity and sit quietly in a cool place.
• Drink clear juice or a sports beverage.
• Do not return to strenuous activity for a few hours after the cramps subside because further exertion may lead to heat exhaustion or heat stroke.
• Seek medical attention for heat cramps if they do not subside in 1 hour.

What is heat rash?

Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It can occur at any age but is most common in young children. Heat rash looks like a red cluster of pimples or small blisters. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases.

What is the best treatment for heat rash?

The best treatment for heat rash is to provide a cooler, less humid environment. Keep the affected area dry. Dusting powder may be used to increase comfort.

Can medications increase the risk of heat-related illness?

The risk for heat-related illness and death may increase among people using the following drugs: (1) psychotropics, which affect psychic function, behavior, or experience (e.g. haloperidol or chlorpromazine); (2) medications for Parkinson’s disease, because they can inhibit perspiration; (3) tranquilizers such as phenothiazines, butyrophenones, and thiozanthenes; and (4) diuretic medications or “water pills” that affect fluid balance in the body.

How effective are electric fans in preventing heat-related illness?

Electric fans may provide comfort, but when the temperature is in the high 90s, fans will not prevent heat-related illness. Taking a cool shower or bath or moving to an air-conditioned place is a much better way to cool off. Air conditioning is the strongest protective factor against heat-related illness. Exposure to air conditioning for even a few hours a day will reduce the risk for heat-related illness. Consider visiting a shopping mall or public library for a few hours.

How can people protect their health when temperatures are extremely high?

Remember to keep cool and use common sense. Drink plenty of fluid, replace salts and minerals, wear appropriate clothing and sunscreen, pace yourself, stay cool indoors, schedule outdoor activities carefully, use a buddy system, monitor those at risk, and adjust to the environment.

How much should I drink during hot weather?

During hot weather you will need to increase your fluid intake, regardless of your activity level. Don’t wait until you’re thirsty to drink. During heavy exercise in a hot environment, drink enough non-alcoholic cool fluids each hour to maintain normal color and amount of urine output.

Should I take salt tablets during hot weather?

Do not take salt tablets unless directed by your doctor. Heavy sweating removes salt and minerals from the body. These are necessary for your body and must be replaced. The easiest and safest way to do this is through your diet. Drink fruit juice or a sports beverage when you exercise or work in the heat.

What is the best clothing for hot weather or a heat wave?

Wear as little clothing as possible when you are at home. Choose lightweight, light-colored, loose-fitting clothing. In the hot sun, a wide-brimmed hat will provide shade and keep the head cool. If you must go outdoors, be sure to apply sunscreen 30 minutes prior to going out and continue to reapply according to the package directions. Sunburn affects your body’s ability to cool itself and causes a loss of body fluids. It also causes pain and damages the skin.

What should I do if I work in a hot environment?

Pace yourself. If you are not accustomed to working or exercising in a hot environment, start slowly and pick up the pace gradually. If exertion in the heat makes your heart pound and leaves you gasping for breath, STOP all activity. Get into a cool area or at least in the shade, and rest, especially if you become lightheaded, confused, weak, or faint.

Hot summer weather can pose special health risks to older adults. The National Institute on Aging (NIA), part of the National Institutes of Health, has some advice for helping older people avoid heat-related illnesses, known as hyperthermia.

Hyperthermia is an abnormally high body temperature caused by a failure of the heat-regulating mechanisms of the body to deal with the heat coming from the environment. Heat fatigue, heat syncope (sudden dizziness after prolonged exposure to the heat), heat cramps, heat exhaustion and heat stroke are commonly known forms of hyperthermia. Risk for these conditions can increase with the combination of outside temperature, general health and individual lifestyle.

Lifestyle factors can include not drinking enough fluids, living in housing without air conditioning, lack of mobility and access to transportation, overdressing, visiting overcrowded places and not understanding how to respond to hot weather conditions. Older people, particularly those with chronic medical conditions, should stay indoors on hot and humid days, especially when an air pollution alert is in effect. People without air conditioners should go to places that do have air conditioning, such as senior centers, shopping malls, movie theaters and libraries. Cooling centers, which may be set up by local public health agencies, religious groups and social service organizations in many communities, are another option.

Health-related factors, some especially common among older people, that may increase risk of hyperthermia include:

• Being dehydrated.
• Age-related changes to the skin such as impaired blood circulation and inefficient sweat glands.
• Heart, lung and kidney diseases, as well as any illness that causes general weakness or fever.
• High blood pressure or other conditions that require changes in diet. For example, people on salt-restricted diets may be at increased risk. However, salt pills should not be used without first consulting a doctor.
• Reduced sweating, caused by medications such as diuretics, sedatives, tranquilizers and certain heart and blood pressure drugs.
• Taking several drugs for various conditions. It is important, however, to continue to take prescribed medication and discuss possible problems with a physician.
• Being substantially overweight or underweight.
• Drinking alcoholic beverages.

Heat stroke is a life-threatening form of hyperthermia. It occurs when the body is overwhelmed by heat and unable to control its temperature. Heat stroke occurs when someone’s body temperature increases significantly (generally above 104 degrees Fahrenheit) and has symptoms such as mental status changes (like confusion or combativeness), strong rapid pulse, lack of sweating, dry flushed skin, faintness, staggering, or coma. Seek immediate emergency medical attention for a person with any of these symptoms, especially an older adult.

If you suspect that someone is suffering from a heat-related illness:

• Get the person out of the heat and into a shady, air-conditioned or other cool place. Urge them to lie down.
• If you suspect heat stroke, call 911.
• Encourage the individual to shower, bathe or sponge off with cool water.
• Apply a cold, wet cloth to the wrists, neck, armpits, and/or groin. These are places where blood passes close to the surface of the skin, and the cold cloths can help cool the blood.
• If the person can swallow safely, offer fluids such as water, fruit and vegetable juices, but avoid alcohol and caffeine.

Your body normally cools itself by sweating. During hot weather, especially when it is very humid, sweating just isn't enough to cool you off. Your body temperature can rise to dangerous levels and you can develop a heat illness.

Most heat illnesses happen when you stay out in the heat too long. Exercising and working outside in high heat can also lead to heat illness. Older adults, young children, and those who are sick or overweight are most at risk. Taking certain medicines or drinking alcohol can also raise your risk.

Heat-related illnesses include

• Heat stroke - a life-threatening illness in which body temperature may rise above 106° F in minutes. Symptoms include dry skin, a rapid, strong pulse, dizziness, nausea, and confusion. If you see any of these signs, get medical help right away.
• Heat exhaustion - an illness that can happen after several days of exposure to high temperatures and not enough fluids. Symptoms include heavy sweating, rapid breathing, and a fast, weak pulse. If it is not treated, it can turn into heat stroke.
• Heat cramps - muscle pains or spasms that happen during heavy exercise. You usually get them in your abdomen, arms, or legs.
• Heat rash - skin irritation from excessive sweating. It is more common in young children.

You can lower your risk of heat illness by drinking fluids to prevent dehydration, replacing lost salt and minerals, and limiting your time in the heat.

Heat cramps usually affect workers who sweat a lot during strenuous activity. This sweating depletes the body’s salt and moisture levels. Low salt levels in muscles cause painful cramps. Heat cramps may also be a symptom of heat exhaustion.

Symptoms

Muscle cramps, pain, or spasms in the abdomen, arms, or legs

First Aid

Workers with heat cramps should do the following:

• Drink water and have a snack or a drink that replaces carbohydrates and electrolytes (such as sports drinks) every 15 to 20 minutes.
• Avoid salt tablets.
• Get medical help if the worker:

• • Has heart problems.
  • Is on a low sodium diet.
  • Has cramps that do not subside within 1 hour.

Heat exhaustion is the body’s response to an excessive loss of water and salt, usually through excessive sweating. Heat exhaustion is most likely to affect:

• The elderly
• People with high blood pressure
• Those working in a hot environment

Symptoms

Symptoms of heat exhaustion include:

• Headache
• Nausea
• Dizziness
• Weakness
• Irritability
• Thirst
• Heavy sweating
• Elevated body temperature
• Decreased urine output

First Aid

Treat a worker who has heat exhaustion by doing the following:

• Take worker to a clinic or emergency room for medical evaluation and treatment.
• Call 911 if medical care is unavailable.
• Have someone stay with the worker until help arrives.
• Remove the worker from the hot area and give liquids to drink.
• Remove unnecessary clothing, including shoes and socks.
• Cool the worker with cold compresses or have the worker wash their head, face, and neck with cold water.
• Encourage frequent sips of cool water.

Heat rash is a skin irritation caused by excessive sweating during hot, humid weather.

Symptoms

Symptoms of heat rash include:

• Red clusters of pimples or small blisters
• Usually appears on the neck, upper chest, groin, under the breasts, and in elbow creases

First Aid

Workers who have heat rash should:

• Work in a cooler, less humid environment, if possible.
• Keep the rash area dry.
• Apply powder to increase comfort.
• Don’t use ointments and creams.

Heat stroke is the most serious heat-related illness. It occurs when the body can no longer control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. When heat stroke occurs, the body temperature can rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause permanent disability or death if the person does not receive emergency treatment.

Symptoms

Symptoms of heat stroke include:

• Confusion, altered mental status, slurred speech
• Loss of consciousness (coma)
• Hot, dry skin or profuse sweating
• Seizures
• Very high body temperature
• Fatal if treatment delayed

First Aid

Take the following steps to treat a worker with heat stroke:

• Call 911 for emergency medical care.
• Stay with the worker until emergency medical services arrive.
• Move the worker to a shaded, cool area and remove outer clothing.
• Cool the worker quickly, using the following methods:

• • With a cold water or ice bath, if possible
  • Wet the skin
  • Place cold wet cloths on the skin
  • Soak clothing with cool water

• Circulate the air around the worker to speed cooling.
• Place cold wet cloths or ice on the head, neck, armpits, and groin; or soak the clothing with cool water.

Heat syncope is a fainting (syncope) episode or dizziness that usually occurs when standing for too long or suddenly standing up after sitting or lying. Factors that may contribute to heat syncope include dehydration and lack of acclimatization.

Symptoms

Symptoms of heat syncope include:

• Fainting (short duration)
• Dizziness
• Light-headedness from standing too long or suddenly rising from a sitting or lying position

First Aid

Workers with heat syncope should:

• Sit or lie down in a cool place.
• Slowly drink water, clear juice, or a sports drink.

Rhabdomyolysis (rhabdo) is a medical condition associated with heat stress and prolonged physical exertion. Rhabdo causes the rapid breakdown, rupture, and death of muscle. When muscle tissue dies, electrolytes and large proteins are released into the bloodstream. This can cause irregular heart rhythms, seizures, and damage to the kidneys.

Symptoms

Symptoms of rhabdo include:

• Muscle cramps/pain
• Abnormally dark (tea or cola-colored) urine
• Weakness
• Exercise intolerance
• Asymptomatic

First Aid

Workers with symptoms of rhabdo should:

• Stop activity
• Drink more liquids (water preferred)
• Seek immediate care at the nearest medical facility.
• Ask to be checked for rhabdomyolysis (i.e., blood sample analyzed for creatine kinase).

Sunburn is an often painful sign of skin damage from spending too much time outdoors without wearing a protective sunscreen. Years of overexposure to the sun lead to premature wrinkling, aging of the skin, age spots, and an increased risk of skin cancer. In addition to the skin, eyes can get burned from sun exposure. Sunburned eyes become red, dry, and painful, and feel gritty. Chronic exposure of eyes to sunlight may cause pterygium (tissue growth that leads to blindness), cataracts, and perhaps macular degeneration, a leading cause of blindness.

Symptoms

Unlike a thermal burn, sunburn is not immediately apparent. Symptoms usually start about 4 hours after sun exposure, worsen in 24-36 hours, and resolve in 3-5 days.

Symptoms may include:

• Red, warm, and tender skin
• Swollen skin
• Blistering
• Headache
• Fever
• Nausea
• Fatigue

The pain from sunburn is worse 6-48 hours after sun exposure. Skin peeling usually begins 3-8 days after exposure.

First Aid

There is no quick cure for minor sunburn:

• Symptoms can be treated with aspirin, acetaminophen, or ibuprofen to relieve pain and headache and reduce fever.
• Drinking plenty of water helps to replace fluid losses.
• Cool baths or the gentle application of cool wet cloths on the burned area may also provide some comfort.
• Workers with sunburns should avoid further exposure until the burn has resolved.
• Additional symptomatic relief may be achieved through the application of a topical moisturizing cream, aloe, or 1% hydrocortisone cream.
• A low-dose (0.5%-1%) hydrocortisone cream, which is sold over the counter, may be helpful in reducing the burning sensation and swelling and speeding up healing.

If blistering occurs:

• Lightly bandage or cover the area with gauze to prevent infection.
• The blisters should not be broken, as this will slow the healing process and increase the risk of infection.
• When the blisters break and the skin peels, dried fragments may be removed and an antiseptic ointment or hydrocortisone cream may be applied.
• Seek medical attention if any of the following occur:
  • Severe sunburns covering more than 15% of the body
  • Dehydration
  • High fever (>101°F)
  • Extreme pain that persists for longer than 48 hours

Extreme temperatures associated with heat waves can make everyone uncomfortable. When combined with conditions such as high humidity, sun exposure, stagnant air, and poor air quality, high temperatures can also become a health concern. Some groups face a greater risk of heat-related illness than others. For instance, outdoor workers and athletes are at greater risk than office workers because they have increased exposure to heat. Other groups may be disproportionately affected by the effects of high heat as a result of age or poor health, or the lack of resources that enable them to adapt or recover. Identifying specific factors that increase risk for some populations gives us a way to reduce exposure and vulnerability through adaptive actions. In some cases, simply increasing awareness of the risks that extreme heat poses to health can encourage people to take adaptive actions, such as going indoors or getting to a cooling center.

Groups most at risk to heat include, but are not limited to: children, older adults, people experiencing homelessness, people with pre-existing conditions, people with disabilities, indoor and outdoor workers, emergency responders, incarcerated people, low income communities, pregnant people, athletes, and more.

Children

As dependents, children rely on others to keep them safe, and some may not have the resources or knowledge to protect themselves from extreme heat. Children spend a good portion of their time in schools or day care settings, some of which may lack air conditioning.

Children are less efficient thermoregulators than adults; they have a smaller cardiovascular output and a higher metabolic rate than adults, which can increase vulnerability. Additionally, children often play outside in structured and unstructured activities. This exposes them to some of the same risks as outdoor workers and athletes experience (see below).

Prevention is the best defense in addressing extreme heat.

• As much as you can, keep children out of direct sun.
• Move outdoor activities to the morning and evening rather than middle of the day.
• Stay hydrated, wear loose and light clothing, and practice sun safety (including wearing sunscreen).

Additionally, never leave children alone in a parked car – temperatures inside a car can rise 20 degrees in just 10 minutes, even with an open window.

Athletes

Athletes are at risk of heat illness due to the combination of exposure, exertion, and, in some cases, wearing protective gear that traps heat. Outdoor activity exposes athletes to high temperatures, and conditions can be exacerbated by direct sunlight and/or poor air quality. Decision makers can use common tools to check current and future forecast air temperatures (NWS Graphical Forecasts), solar exposure (the opposite of cloud cover), and air quality (AirNow Air Quality Forecast), and factor those conditions into decisions about where and when to conduct practices and competitions.

As athletes are expected to push themselves physically, the line between acceptable levels of exertion and dangerous levels of exertion during heat may be blurred.

A range of organizations offer information about the risk heat poses to athletes. While many athletes have suffered from complications due to overheating, the death of Korey Stringer, who was participating in a National Football League training camp in 2001 when he suffered heat stroke, led to the creation of an eponymous institute at the University of Connecticut for the prevention of such deaths in the future. This is one organization that conducts research and issues guidance for the prevention of heat-related morbidity and mortality in athletes.

Older Adults

For older adults, health complications such as cardiovascular issues can exacerbate the effects of extreme heat. Adults who require life-sustaining devices may be disproportionately affected during power outages that commonly accompany extreme heat events. Additionally, those who need constant access to oxygen, prescription drugs, or other consumable medical resources may not feel comfortable leaving their homes during a heat wave. Some older adults may also be using prescription drugs that affect their capability to thermoregulate or that block nerve impulses,2 both of which increase vulnerability to thermal extremes. Additionally, certain conditions, such as different types of dementia, can also affect a person's reactions and choices related to taking self protective actions, increasing risk of harm during a heat event. The CDC offers information to help you recognize the signs of heat-related distress in older adults, and find tips you can offer to help them keep cool.

Older adults are also more likely to be socially isolated than some groups, as they are less likely to have occupations and may lack other community involvement. Empirical studies have documented the increased risk of morbidity and mortality due to extreme heat among older people.2 Older populations may be concentrated in retirement communities in states such as Florida or Colorado (where the Colorado Climate Change Vulnerability Study predicts a 125 percent increase in such populations by 2030). Such dense clusters of older residents may put extra pressure on early responders and health care facilities during extreme heat in these areas. Finally, urban settings, with high rise structures and the urban heat island effect, may increase the risk of heat illness substantially, yet rural settings have factors such as social isolation and lack of transport or services which can also increase risk.

The first step in addressing the risk of heat illness among older adults is understanding where they live. The U.S. Environmental Protection Agency’s EJSCREEN tool helps decision makers examine demographic variables that may influence environmental health outcomes. For example, users can produce maps showing “percent of population over age 64." Additionally, the U.S. Department of Health and Human Services' emPOWER Map can show where Medicare beneficiaries or those who rely upon electricity-dependent medical and assistive equipment reside. Older residents may also be less likely to have or use air conditioners because of the expense of electricity. The HHS Low Income Home Energy Assistance Program (LIHEAP) can assist with this issue.

Tips for older adults include:

• Do not stay home alone during a summer power outage or an extreme heat event.

• Make sure a trusted friend or relative has an extra key to your home, knows where you keep your emergency supplies and can use lifesaving equipment or administer medicine.

• Drink fluids regularly to avoid getting dehydrated and overheated. Talk to your doctor about whether you need fluids with extra electrolytes in the heat.

• Be careful with the amount of time you spend outdoors. Take frequent breaks to come back inside, cool off, and drink fluids that don’t have caffeine.

Pregnant People

For pregnant people, extreme heat can be quite uncomfortable. Discomfort occurs not only because pregnant people tend to experience a general increase in their core body temperature regardless of the air temperature, but also because extreme heat events can increase the likelihood of common challenges during pregnancy, such as excessive sweating and heat rash. Importantly, extreme heat also poses health risks for a pregnant people and her developing fetus. There is increasing evidence that extreme heat can increase the risk for preterm birth, low birth weight, fetal death, and infant mortality.

Emergency Responders

Emergency responders put themselves in danger repeatedly in the line of duty, and heat waves are no exception. Police officers, firefighters, paramedics, and the many others who protect people during heat waves need information to understand how to find and help those who are most disproportionately affected, while ensuring they are protected themselves. In order to support this population, the Federal Emergency Management Agency (FEMA) U.S. Fire Administration and the International Association of Fire Fighters (IAFF) developed the Emergency Incident Rehabilitation (PDF) report to inform decision makers of heat exposures that firefighters and other emergency responders face. The IAFF also hosts the Emergency Incident Rehabilitation Program, which contains training resources and other information.

Before an extreme heat event, emergency responders must prepare themselves to tend to members of groups experiencing disproportionate impacts. The CDC tool Assessing Health Vulnerability to Climate Change: A Guide for Health Departments guides health departments in assessing local vulnerabilities to the health hazards associated with climate change. It's also important to assure the continuity of operations of vital health care resources during extreme heat events. The Sustainable and Climate-Resilient Health Care Facilities Toolkit provides information to build resilience of healthcare organizations.

When planning for extreme weather events that could knock out power and/or reduce transportation options, the emPOWER Map can be used to understand where Medicare beneficiaries or those who rely upon electricity-dependent medical and assistive equipment reside. People with mental health conditions (including older adults and those taking prescription medications that impair the body's ability to regulate temperature) can also be at increased risk of disease and death in extreme heat: the Substance Abuse and Mental Health Services Administration provides helpful information for serving these populations. Finally, a range of forecasting tools can keep you apprised of upcoming heat events on many time scales.

Outdoor and Indoor Workers

People who work outdoors—in agriculture, fishing, construction, or other service areas—or in situations where they don't have access to air conditioning are at risk for heat-related illnesses and injuries. These workers may have job tasks requiring great physical exertion, and the use of personal protective clothing and equipment may trap heat and prevent cooling. Many of these workers, particularly farm workers, may not have easy and quick access to water and shade. Lack of acclimatization in new workers and during heat waves also puts workers at higher risk. Some outdoor workers may also suffer from increased temperatures in cities due to the urban heat island effect, which can increase temperatures by 18 to 27°F (10 to 15°C) during the day, and 9 to 18°F (5 to 10°C) at night in urban areas compared to rural areas.

Photo courtesy of OSHA

People with Disabilities

Many people with disabilities are at a higher risk of heat-related illness during periods of high daytime and nighttime temperatures. Approximately one in four adults in the United States has a disability, and extreme heat can cause them significant adverse impacts, and even death. People with disabilities are two to four times more likely to be injured or killed in a natural disaster, and heat waves triple the risk of death for people with preexisting psychosocial disabilities.

During chronic or acute heat events, people with physical, sensory, mental, or cognitive disabilities are disproportionately affected. The increase in heat events across the nation impacts people with disabilities’ ability to recover and adapt after an extreme weather event. Additionally, heatwaves can affect many populations over a short period of time, which may overwhelm healthcare and emergency response capacity and disrupt transportation and communications systems. Because disruption to these systems can seriously impact people with disabilities, it is important to include people with disabilities as central stakeholders and community members when planning for them.

It is important to note that individuals with disabilities are protected from discrimination by civil rights laws including the Americans with Disabilities Act and the Rehabilitation Act. These laws require government agencies and many of their nongovernmental partners to affirmatively plan for and meet the needs of individuals with disabilities in disasters. These obligations typically include ensuring programmatic and effective communication access for individuals with disabilities and providing reasonable modification of policies, practices, and procedures to ensure access.

What heat related concerns can people with disabilities experience?

• Exposure to heat may result in more severe health risks or death because it exacerbates preexisting conditions, including cerebral, respiratory, and cardiovascular diseases
• Heat has an impact on those who are taking medications that may affect the body’s ability to regulate its temperature (for example: antidepressants and mood stabilizers)
• Emergency warnings and other important public messaging may not be accessible or consider the needs of people with disabilities. Inaccessible public warnings and information that doesn’t include information regarding people with disabilities may make it difficult for people with low vision or blindness, hearing loss, or mobility issues to receive actionable information and plan for extreme weather events.
• People with disabilities may rely on long-term services and supports, such as personal assistance services (PAS), meal delivery, or other in-home supports, which can be disrupted before, during, and after a natural disaster or extreme weather event.
• Extreme heat events can force people to leave their residences to seek cooling relief, or can cause people to be stranded in their homes unexpectedly where they may, in some situations such as a blackout, experience deadly indoor temperatures.
• Some people with disabilities may need accessible public transportation to access cooling centers and cooling center facilities to be accessible.
• Dementia is a risk factor for hospitalization and death during heat waves.
• People with disabilities experience disproportionately higher rates of social risk factors, such as poverty and lower educational attainment, that contribute to poorer health outcomes during extreme events or climate-related emergencies.

Heat and Spinal Cord Injuries

People with spinal cord injuries are especially at risk during high temperatures because of their inability to control their body temperature. Spinal cord injuries can lead to reduced sweating capacity, the body's natural way to cool itself off. Prolonged periods without water or sustained periods of intense heat could accelerate adverse reactions to extreme temperatures in someone who lacks the ability to naturally thermoregulate. Equitable access to cooling systems during recovery, including water, is the only way to reduce risks to persons with spinal cord injury or disease.

Heat and Mental Health

People with mental health and substance use conditions are especially susceptible to heat. Sleep loss during periods of prolonged, extreme heat may be a contributing stressor for mental health and substance use conditions. Psychotropic medications may increase risk, and use of alcohol and other substances also can place people at more risk of har. People with severe mental health conditions, such as schizophrenia, are at risk during hot weather because their medications may interfere with temperature regulation or even directly cause hyperthermia.

Heat and Cognitive Disabilities

Cognitive disabilities, such as intellectual disabilities, Alzheimer’s disease and, dementia, can impact a person’s ability to comprehend symptoms and/or communicate the effects they are experiencing. Certain cognitive disabilities can also affect a person's ability to take self-protective actions, increasing risk of harm during a heat event.

Impacts of Heat on Infrastructure and Power Outages

Extreme heat can damage or destroy critical infrastructure and facilities. The disruption to critical services disproportionately and negatively impacts people with disabilities and puts individuals at increased risk. Temperature increases and heatwaves can lead to brownouts or blackouts. Power outages can jeopardize the health and safety of people with disabilities, older adults, and people with serious health conditions, who often depend on equipment powered by electricity.

During a power outage, people with disabilities may lose access to medications, durable medical equipment, and alternate and assistive communication devices. Life- saving medications, such as insulin, need to be refrigerated. Power outages also affect life-sustaining medical equipment, such as oxygen or mobility equipment. Additionally, people who depend on electric medical devices, such as a ventilator, and people who require dialysis, or need power for wheelchairs are also at high risk during a power outage.

Tips for people who are dealing with loss of power during heat:

• Develop a plan to use caregivers, neighbors, family, and friends to address your heat-related needs. Communicate with them to let them know how they can best support you.
• Keep a cooler and cold packs nearby to help keep refrigerated medicine, like insulin, cool during a power outage.
• Know the phone numbers and locations for local medical facilities, such as hospitals or medical clinics, to create contingency plans if you cannot access a cooling center, lose power, or need more help.
• If a person is facing a barrier to accessing air conditioned or cooler environments (such as during a blackout), one good way to cool down is to take a bath or shower.
• If you are in need of medical care, call 911

Actions to take to decrease heat risk for people with disabilities:

• Consult your pharmacist or a professional to talk about the types of heat risks that could be a side-effect prescribed medications and self-protective actions to reduce your heat related risk.
• Prepare for an emergency, including heat-related emergencies by having an emergency plan and a kit with medication, food, water, first-aid supplies, and copies of medical records.
• Connect with your local emergency manager to make them aware of your functional needs and to identify resources that they have can you, if needed, during an emergency.

Access the links in the tab below for more resources, tips, and guides for people with disabilities.

People with Chronic Health Conditions

Extreme heat can be dangerous for anyone, but it can be especially dangerous for those with chronic medical conditions. High daytime and nightime temperatures can cause stress on the human body which exacerbates health conditions such as respiratory and cardiovascular diseases, diabetes, and renal disease. Some medical conditions, such as obesity and heart disease, increase people’s sensitivity to heat, putting them at greater risk of heat illnesses. In addition, some medications (such as some antidepressants, diuretics, and beta-blockers) taken for a chronic illness may increase an individual’s sensitivity to heat by interfering with the body’s ability to regulate temperature, fluids, or electrolytes.

Why are people with chronic medical conditions more disproportionately affected by extreme heat?

• They may be less likely to sense and respond to changes in temperature.
• They may be taking medications that can make the effect of extreme heat worse.
• Conditions like heart disease, mental illness, poor blood circulation, and obesity are risk factors for heat-related illness. Individuals who are overweight or obese tend to retain more body heat.

Heat and Cardiovascular Conditions

Prolonged heat exposure from extreme heat places an increased strain on the heart and may lead to heat-related illness if the cardiovascular system fails to properly thermoregulate internal body temperature. Individuals with already weakened cardiovascular systems have a heightened risk of heat-related morbidity and mortality, as their hearts may not be able to meet the increased demand required to rid the body of the excess heat. In older adults and those with pre-existing cardiovascular conditions (e.g., ischemic heart disease (IHD), coronary heart disease (CHD), heart failure (HF)), the heart is not as proficient at meeting the increased demand required to rid the body of the excess heat. Individuals that belong to these populations are more susceptible to adverse health outcomes from extreme heat exposure. Additionally, there is evidence of combined effects of air pollution and extreme heat on cardiovascular mortality, especially in urban areas

Heat and Mental Health

People with mental health conditions are particularly at-risk to heat-related illnesses. For example, some medications can increase a person’s risk for heat-related illness. Certain conditions, such as different types of dementia, can affect an individual’s judgment or reactions, increasing the risk of harm during a heat event. People with an existing mental health conditions are also more at risk for distress and other mental health effects following extreme heat. Medical conditions like Alzheimer’s disease can impair judgment and behavioral responses in crisis situations, which can place people with those conditions at greater risk. The risk of death also increases during event for people with psychosis, dementia, and substance misuse. Hospital admissions have been shown to increase for those with mental health conditions as a result of extreme heat, increasing ambient temperatures, and humidity.

People taking certain psychotropic medications may experience more side effects than usual when temperatures increase. Psychotropic medications are drugs that affect how the brain works and cause changes in mood, awareness, thoughts, feelings, or behavior. These medications are used in mental health therapy and treatment and are taken by both children and adults. Types of psychotropic medications include antidepressants, anti-anxiety medications, stimulants, antipsychotics, and mood stabilizers. Some psychotropic medications can interfere with a person’s ability to regulate heat and their awareness that their body temperature is rising, which is associated with injury and death.

Heat and Diabetes

People who have type 1 or type 2 diabetes feel the heat more than people who don’t have diabetes. This is due to:

• Certain diabetes complications, such as damage to blood vessels and nerves, can affect your sweat glands so your body can’t cool as effectively. That can lead to heat exhaustion and heat stroke, which is a medical emergency.
• People with diabetes get dehydrated (lose too much water from their bodies) more quickly. Not drinking enough liquids can raise blood sugar, and high blood sugar can make you urinate more, causing dehydration. Some commonly used medicines like diuretics (“water pills” to treat high blood pressure) can dehydrate you, too.
• High temperatures can change how your body uses insulin. You may need to test your blood sugar more often and adjust your insulin dose and what you eat and drink

Tips for People with Diabetes

• Don’t store insulin or oral diabetes medicine in direct sunlight or in a hot car. Check package information about how high temperatures can affect insulin and other medicines.
• If you’re traveling, keep insulin and other medicines in a cooler. Don’t put insulin directly on ice or on a gel pack.
• Check your blood sugar before, during, and after you’re active. You may need to change how much insulin you use. Ask your doctor if you would like help in adjusting your dosage.
• Heat can damage your blood sugar monitor, insulin pump, and other diabetes equipment. Don’t leave them in a hot car, by a pool, in direct sunlight, or on the beach. The same goes for supplies such as test strips.

Tips for People with Chronic Health Conditions:

• Work with your support network if you have one - caregivers, neighbors, family and friends - to monitor and address your heat-related needs. Have them check in with you regularly to ensure you are safe and healthy.
• Read the side effects of medications and talk with your doctor about how heat exposure will interact with them.
• Keep a cooler and cold packs nearby to help keep refrigerated medicine, like insulin, cool during a power outage.
• Know the phone numbers and locations for local medical facilities, such as hospitals or nursing homes, to create contingency plans if you cannot access a cooling center, lose power, or need more help.

Pets and Service and Support Animals

Pet and service and support animal owners should take special precautions to safeguard the health of their animals during extreme heat. All animals have different thermoneutral zones (TNZs)—ranges of temperatures within which their bodies needn’t work to stay warm (for example, by shivering) or cool (for example, by sweating or panting). In some cases, the TNZs may be somewhat close to humans’ (domestic dogs), while in other cases the TNZs may be skewed higher (domestic cats) or lower. Small animals, such as rodents, may be at increased risk for the same reason as children—their metabolic rate is much higher than larger animals due to their small size. Additionally, some of the same characteristics that make some humans more vulnerable than others are also in play with other animals, such as older or very young pets and pets with existing health conditions. Watch for warning signs, such as heavy panting or glazed eyes, because animals cannot tell you when they are too hot. Another risk to pets and service animals is the potential for burns to their paws and pads as paved surfaces may become excessively hot during a heat wave.

An additional factor to consider regarding pet and service and support animal ownership is that having an animal may influence the behavior of people in maladaptive ways during heat waves. For example, reluctance to leave a pet behind while seeking medical care for oneself or uncertainty as to whether a pet will be accepted at a cooling center could cause pet owners to remain in a hot building when it is unsafe. As a precaution, consider calling cooling centers well in advance of heat waves or heat season to determine if those nearest you will accept pets.

As we age, our ability to adequately respond to summer heat can become a serious problem. Older people are at significant increased risk of heat-related illnesses, known collectively as hyperthermia, during the summer months. Hyperthermia can include heat stroke, heat edema (swelling in your ankles and feet when you get hot), heat syncope (sudden dizziness after exercising in the heat), heat cramps, and heat exhaustion.

Experts at the National Institute on Aging, part of the National Institutes of Health, say knowing which health-related factors may increase risk could save a life. Those factors include:

• Age-related changes to the skin such as poor blood circulation and inefficient sweat glands
• Heart, lung, and kidney diseases, as well as any illness that causes general weakness or fever
• High blood pressure or other conditions that require changes in diet, such as salt-restricted diets
• Reduced sweating, caused by medications such as diuretics, sedatives, tranquilizers, and certain heart and blood pressure drugs
• Taking several drugs for various conditions (It is important, however, to continue to take prescribed medication and discuss possible problems with a physician.)
• Being substantially overweight or underweight
• Drinking alcoholic beverages
• Being dehydrated

Lifestyle factors can also increase risk, including extremely hot living quarters, lack of transportation, overdressing, visiting overcrowded places, and not understanding how to respond to weather conditions.

Older people, particularly those at special risk, should stay indoors on particularly hot and humid days, especially when there is an air pollution alert in effect. To stay cool, drink plenty of fluids and wear light-colored, loose-fitting clothes in natural fabrics. People without fans or air conditioners should keep their homes as cool as possible or go someplace cool. Senior centers, religious groups, and social service organizations in many communities provide cooling centers when the temperatures rise. Or visit public air conditioned places such as shopping malls, movie theaters, or libraries.

Heat stroke is a severe form of hyperthermia that occurs when the body is overwhelmed by heat and unable to control its temperature. Someone with a body temperature above 104 degrees Fahrenheit is likely suffering from heat stroke. Symptoms include fainting; a change in behavior (confusion, combativeness, staggering, possible delirium or coma); dry, flushed skin and a strong, rapid pulse; and lack of sweating. Seek immediate medical attention for a person with any of these symptoms, especially an older adult.

If you suspect that someone is suffering from a heat-related illness:

• Call 911 if you suspect heat stroke.
• Get the person out of the heat and into a shady, air-conditioned or other cool place. Urge them to lie down.
• If the person can swallow safely, offer fluids such as water and fruit or vegetable juices, but not alcohol or caffeine.
• Apply a cold, wet cloth to the wrists, neck, armpits, and groin. These are places where blood passes close to the surface of the skin, and a cold cloth can help cool the blood.
• Encourage the person to shower, bathe, or sponge off with cool water if it is safe to do so.

The term hyperthermia refers to heat-related illness—or those illnesses associated with exposure to high temperatures in the environment, causing high body temperature.

When the body is exposed to high temperatures, as on a hot day, the body normally cools itself using different mechanisms, such as heavy sweating and losing heat through the skin. But in certain situations, such as when a person is inside a parked car when it is warm or sunny, sweating and other mechanisms may not be enough to cool high body heat. As a result, the body's temperature rises quickly and may damage the brain and other organs in the body. Normal body temperature is 98.6 degrees Fahrenheit.

Hyperthermia occurs when the body heats up to 104 degrees Fahrenheit. A body temperature of 107 degrees is usually fatal.

Infants' immature body systems are not able to cope with high temperatures, and infants are not able to communicate if they are too warm. That's why they are at especially high risk of hyperthermia.

According to the AAP, deaths from hyperthermia have increased in the last decade, especially among children and pets, mainly as a result of their being left alone in a car for even short periods of time. Even when the air outside is at "room temperature" (about 72 degrees Fahrenheit), the temperature inside a car can increase to more than 100 degrees Fahrenheit in just 30 minutes. One study showed that on a sunny, 72-degree day, the temperature inside a car can reach 117 degrees Fahrenheit, and cracking the windows did not decrease the rate of the rise in temperature. Thus, even when the weather is comfortable outside, children are at high risk for heat stroke and death from being left alone in a car.

Parents and caregivers should never leave a child alone in a car, not even with the windows down, and not even for a minute. In addition, parents and caregivers should develop plans for getting everyone out of the car to ensure that they all exit the car safely and no one is left in the car accidentally.

If you see a child left alone in a parked car, you should call 911 to request emergency help. It could mean the difference between life and death for that child.

Stay Cool

Wear Appropriate Clothing: Choose lightweight, light-colored, loose-fitting clothing.

Stay Cool Indoors: Stay in an air-conditioned place as much as possible. If your home does not have air conditioning, go to the shopping mall or public library—even a few hours spent in air conditioning can help your body stay cooler when you go back into the heat. Call your local health department to see if there are any heat-relief shelters in your area.

• Keep in mind: Electric fans may provide comfort, but when the temperature is in the high 90s, they will not prevent heat-related illness. Taking a cool shower or bath or moving to an air-conditioned place is a much better way to cool off. Use your stove and oven less to maintain a cooler temperature in your home.

Schedule Outdoor Activities Carefully: Try to limit your outdoor activity to when it’s coolest, like morning and evening hours. Rest often in shady areas so that your body has a chance to recover.

Pace Yourself: Cut down on exercise during the heat. If you’re not accustomed to working or exercising in a hot environment, start slowly and pick up the pace gradually. If exertion in the heat makes your heart pound and leaves you gasping for breath, STOP all activity. Get into a cool area or into the shade, and rest, especially if you become lightheaded, confused, weak, or faint.

Wear Sunscreen: Sunburn affects your body’s ability to cool down and can make you dehydrated. If you must go outdoors, protect yourself from the sun by wearing a wide-brimmed hat, sunglasses, and by putting on sunscreen of SPF 15 or higher 30 minutes prior to going out. Continue to reapply it according to the package directions.

• Tip: Look for sunscreens that say “broad spectrum” or “UVA/UVB protection” on their labels- these products work best.

Do Not Leave Children in Cars: Cars can quickly heat up to dangerous temperatures, even with a window cracked open. While anyone left in a parked car is at risk, children are especially at risk of getting a heat stroke or dying. When traveling with children, remember to do the following:

• Never leave infants, children or pets in a parked car, even if the windows are cracked open.
• To remind yourself that a child is in the car, keep a stuffed animal in the car seat. When the child is buckled in, place the stuffed animal in the front with the driver.
• When leaving your car, check to be sure everyone is out of the car. Do not overlook any children who have fallen asleep in the car.

Avoid Hot and Heavy Meals: They add heat to your body!

Stay Hydrated

Drink Plenty of Fluids: Drink more fluids, regardless of how active you are. Don’t wait until you’re thirsty to drink.

• Warning: If your doctor limits the amount you drink or has you on water pills, ask how much you should drink while the weather is hot.
• Stay away from very sugary or alcoholic drinks—these actually cause you to lose more body fluid. Also avoid very cold drinks, because they can cause stomach cramps.

Replace Salt and Minerals: Heavy sweating removes salt and minerals from the body that need to be replaced. A sports drink can replace the salt and minerals you lose in sweat.

• If you are on a low-salt diet, have diabetes, high blood pressure, or other chronic conditions, talk with your doctor before drinking a sports beverage or taking salt tablets.

Keep Your Pets Hydrated: Provide plenty of fresh water for your pets, and leave the water in a shady area.

Stay Informed

Check for Updates: Check your local news for extreme heat alerts and safety tips and to learn about any cooling shelters in your area.

Know the Signs: Learn the signs and symptoms of heat-related illnesses and how to treat them.

Use a Buddy System: When working in the heat, monitor the condition of your co-workers and have someone do the same for you. Heat-induced illness can cause a person to become confused or lose consciousness. If you are 65 years of age or older, have a friend or relative call to check on you twice a day during a heat wave. If you know someone in this age group, check on them at least twice a day.

Monitor Those at High Risk: Although anyone at any time can suffer from heat-related illness, some people are at greater risk than others:

• Infants and young children
• People 65 years of age or older
• People who are overweight
• People who overexert during work or exercise
• People who are physically ill, especially with heart disease or high blood pressure, or who take certain medications, such as for depression, insomnia, or poor circulation

Visit adults at risk at least twice a day and closely watch them for signs of heat exhaustion or heat stroke. Infants and young children, of course, need much more frequent watching.