Who is at heightened risk for hypothermia?
Hypothermia occurs when the body's temperature drops to a dangerously low level, typically below 95°F (35°C). While severe exposure to cold is the primary trigger, a person's risk is influenced by a number of factors beyond just the weather. The body's ability to conserve or generate heat can be compromised by age, health, and lifestyle, making certain populations especially susceptible.
Older adults
Older adults, particularly those over 65, face a higher risk of hypothermia for several reasons. As the body ages, its ability to regulate temperature becomes less efficient. The subcutaneous fat layer, which provides insulation, thins over time, and blood flow can be less efficient due to age-related circulatory changes. Some seniors may also have chronic conditions like diabetes, heart disease, or arthritis that impair their response to cold. Furthermore, financial constraints can lead some older adults to set their thermostats too low, putting them at risk even indoors. People with cognitive impairments like dementia may also wander or not dress appropriately for the weather, increasing their exposure.
Infants and young children
Infants and toddlers lose body heat more rapidly than adults due to their larger body surface area relative to their weight. Their thermoregulatory systems are not fully developed, making them less able to shiver effectively or conserve heat. Infants are also entirely dependent on caregivers to protect them from cold environments. This risk is particularly acute for babies sleeping in cold rooms, and can be exacerbated by inadequate clothing or bedding.
People experiencing homelessness and outdoor workers
Individuals experiencing homelessness are among the most vulnerable to hypothermia due to prolonged, unavoidable exposure to the elements. They often lack adequate shelter, warm clothing, and nutrition, all of which are critical for maintaining body temperature in cold conditions. Outdoor workers, such as construction crews or utility workers, can also be at risk, especially if they are not properly dressed or acclimatized to the cold.
Individuals with substance abuse issues
Alcohol and certain drugs interfere with the body's natural temperature regulation. Alcohol, for instance, creates a false sense of warmth by causing blood vessels to expand, leading to a more rapid loss of body heat. It also impairs judgment, increasing the likelihood that a person will stay in a cold environment without adequate protection.
Who is at heightened risk for hyperthermia?
Hyperthermia is an abnormally high body temperature that can lead to heat exhaustion or heat stroke, a life-threatening emergency. While hot weather is the most common cause, several personal and environmental factors can increase a person's susceptibility.
Older adults
Just as with cold, older adults are also highly vulnerable to heat-related illness. Their bodies' sweat glands may not function as effectively, and the cardiovascular system may be less able to increase blood flow to the skin to facilitate cooling. Additionally, many older adults take medications that interfere with temperature regulation or hydration. Those living alone or with limited mobility may also be less able to seek out cooler environments.
Infants and young children
Babies and young children have immature thermoregulatory systems and a higher body surface area to volume ratio, which causes them to absorb heat more quickly. They also have a lower sweating rate and smaller blood volume, making them more prone to dehydration. Infants are completely dependent on caregivers to protect them from overheating, and tragic cases of heat stroke can occur when infants are left in hot cars. Parents should also be mindful of over-bundling and heavy bedding, which can increase heat stress.
Outdoor workers and athletes
Individuals who engage in strenuous physical activity in hot environments are at high risk for hyperthermia. This includes outdoor workers in industries like agriculture or construction, as well as athletes training or competing in the heat. Lack of acclimatization, dehydration, and wearing heavy clothing or personal protective equipment (PPE) can significantly increase their risk.
Individuals with chronic conditions
Many medical conditions can impair the body's ability to cope with heat. People with heart disease, diabetes, or high blood pressure may have compromised cardiovascular function, making it harder to circulate blood effectively. Obesity also increases heat stress, as it adds a layer of insulation that retains body heat.
Factors increasing vulnerability to both temperature extremes
Dehydration
Adequate hydration is essential for the body's thermoregulation. Dehydration can impair the body's ability to sweat, hindering heat dissipation. In cold weather, it can contribute to reduced blood volume and poor circulation, increasing the risk of frostbite and hypothermia. Vulnerable individuals, such as the very young, very old, and those with certain medical conditions, are at particular risk of becoming dehydrated.
Medications
Many common medications can affect the body's ability to regulate temperature, increasing the risk of both hypothermia and hyperthermia. Some psychiatric medications, for example, can impair sweating, while others, like diuretics, can cause dehydration. Individuals on such medications should be extra vigilant about protecting themselves from extreme temperatures. For more information, the Centers for Disease Control and Prevention offers guidance on managing medications in hot weather: Heat and Medications – Guidance for Clinicians.
Socioeconomic factors
Socioeconomic status plays a significant role in determining a person's vulnerability to temperature-related illness. Lack of access to adequate heating or cooling, particularly for low-income families and older adults, can be a major risk factor. People living in poorly insulated homes or urban areas with limited green spaces can experience higher indoor temperatures during heat waves.
Comparison of vulnerable groups for hypothermia vs. hyperthermia
| Vulnerable Group | Key Hypothermia Risks | Key Hyperthermia Risks |
|---|---|---|
| Older Adults | Inefficient thermoregulation, thinner insulating fat layer, poor circulation, chronic illnesses, financial constraints leading to poor heating. | Impaired sweating, cardiovascular issues, side effects from medication, living alone, lack of access to AC. |
| Infants/Young Children | Larger surface area to volume ratio, immature thermoregulatory system, dependent on caregivers for protection. | Immature thermoregulatory system, lower sweating rate, higher surface area to volume ratio, dependent on caregivers. |
| Homeless/Outdoor Workers | Direct and prolonged exposure to cold weather without adequate shelter, clothing, or nutrition. | High physical exertion in hot environments, lack of acclimatization, dehydration. |
| Individuals with Substance Abuse | Impaired judgment, decreased perception of cold, increased heat loss due to alcohol-induced vasodilation. | Dehydration, impaired judgment, reduced perception of heat, interference with sweating from certain drugs. |
| People with Chronic Illness | Poor circulation (heart disease, diabetes), impaired nerve function (neuropathy, spinal cord injury), effects of certain medications. | Cardiovascular disease, diabetes, obesity, impaired sweating from certain medications. |
Conclusion
While anyone can be affected by extreme temperature conditions, certain groups are far more vulnerable to developing hypothermia or hyperthermia due to a combination of physiological, medical, and socioeconomic factors. Older adults and infants represent a particularly high-risk demographic for both conditions because of their impaired thermoregulation. However, people experiencing homelessness, outdoor workers, individuals with chronic health conditions, and those with substance abuse issues also face significant dangers from extreme temperatures. Understanding these risk factors is the first step toward effective prevention, which includes providing adequate shelter, proper clothing, hydration, and monitoring those most susceptible during both hot and cold weather events.
