How does extreme heat affect the body?
Our Medical Director, Dr Tang featured in the press with his expert advice on the effects extreme heat can have on the body.
What is physically happening to the brain, skin, eyes, nausea, diarrhoea, digestion, lungs (breathing in hot air), feet and ankles swelling etc
Extreme heat can have profound effects on the human body, and prolonged exposure to high temperatures can lead to various heat-related illnesses. The most common examples are:
- Heat Cramps: Heat cramps are painful muscle contractions that occur during or after intense physical activity in high temperatures. They result from electrolyte imbalances and dehydration.
- Heat Exhaustion: Heat exhaustion is a more severe condition resulting from prolonged exposure to high temperatures and inadequate fluid intake. Symptoms may include heavy sweating, weakness, dizziness, nausea, headache, rapid heartbeat, and cool, moist skin.
- Heatstroke: Heatstroke is a life-threatening condition and the most severe form of heat-related illness. It occurs when the body's temperature regulation system fails, and body temperature rises to a dangerous level. Symptoms can include a high body temperature (above 40°C), altered mental state, confusion, dizziness, hot and dry skin, rapid heartbeat, and loss of consciousness. Heatstroke requires immediate medical attention.
- Dehydration: Extreme heat can lead to excessive fluid loss through sweating, leading to dehydration. Dehydration can cause fatigue, weakness, dizziness, increased heart rate, and reduced urine output. When the body becomes dehydrated, it may attempt to conserve water by absorbing more fluid from the colon, resulting in looser stools and diarrhoea.
- Heat Rash: Heat rash, also known as prickly heat, can occur in hot and humid conditions when sweat ducts become clogged, leading to small red bumps or blisters on the skin.
- Respiratory Distress: In extreme heat, the air can become dry, hot, and polluted. This can irritate the respiratory system and exacerbate existing respiratory conditions such as asthma.
- Cardiovascular Strain: High temperatures can place extra stress on the cardiovascular system, as the body works harder to cool itself down. This can lead to an increased heart rate, elevated blood pressure, and potentially exacerbate underlying heart conditions.
- Cognitive Impairment: High temperatures can impair cognitive function, affecting attention, memory, decision-making, and concentration. Heat-related cognitive impairment can lead to decreased productivity, impaired judgment, and increased risk of accidents or mistakes.
- Fatigue and Lethargy: High temperatures can cause fatigue and lethargy, making it more challenging to concentrate and perform mental tasks effectively. Heat-induced fatigue can lead to decreased alertness and overall mental and physical sluggishness.
- Swollen Ankles/Feet: In hot weather, the body may retain more fluid as a response to heat and dehydration. This can lead to swelling in the feet and ankles. When the body senses dehydration, it tries to hold onto water, leading to fluid accumulation in the lower extremities.
It's important to note that extreme heat affects individuals differently, and certain factors like age, underlying health conditions, and overall physical fitness can influence susceptibility to heat-related illnesses.
-Why are babies and old people more affected by extreme heat?
Babies and older people are more susceptible to the effects of extreme heat due to various factors, including their physiological differences and reduced ability to regulate body temperature. Some reasons why they may be at greater risk include:
- Thermoregulation: Infants and older individuals have a less efficient thermoregulatory system compared to adults. They may struggle to regulate their body temperature effectively in response to changes in the environment, making them more vulnerable to extreme heat.
- Dehydration: Babies and older people may be more prone to dehydration due to factors such as reduced fluid intake, limited mobility, or an inability to communicate their thirst effectively. Dehydration can exacerbate the negative effects of heat on the body.
- Reduced Heat Tolerance: Older adults may have a decreased ability to tolerate heat due to age-related changes in the body, such as a reduced sweat response and a decreased ability to dissipate heat. This can lead to a faster onset of heat-related illnesses.
- Underlying Health Conditions: Both infants and older individuals may have pre-existing health conditions that can further compromise their ability to cope with extreme heat. For example, older adults may have cardiovascular diseases or respiratory conditions that make them more susceptible to heat-related complications.
- Medications: Certain medications commonly taken by older adults can affect thermoregulation and increase sensitivity to heat. These may include diuretics, beta-blockers, antihistamines, and some psychiatric medications.
Given these factors, it's crucial to take extra precautions to protect babies and older people during periods of extreme heat. This includes ensuring proper hydration, providing cool and well-ventilated environments, dressing them in lightweight and breathable clothing, and regularly monitoring their well-being for any signs of heat-related illnesses.
How hot is too hot for the human body to survive in?
The human body has a limited ability to tolerate high temperatures, and prolonged exposure to extreme heat can be dangerous and potentially life-threatening. The exact threshold for survival depends on various factors, including individual health, humidity, clothing, and activity level. However, a core body temperature above 40 degrees Celsius is generally considered potentially life-threatening, as it can lead to heatstroke and organ failure.
It's important to note that heat tolerance can vary among individuals, and some people may be more susceptible to heat-related illnesses, such as the elderly, young children, and individuals with certain medical conditions. In such cases, lower temperatures may be considered too hot for survival.
What can people do to protect themselves from the heat if they have to go out in it?
It's essential to prioritise skin protection and adopt sun-safe practices if you have to go out in the sun in order to reduce the risk of skin damage and maintain skin health. This includes wearing sunscreen, seeking shade during peak sun hours, wearing protective clothing, and using sunglasses and wide-brimmed hats.
Does sunscreen stop working at a certain temperature or light intensity?
Sunscreen does not stop working at a specific temperature or light intensity, but its effectiveness can be influenced by various factors.
Sun Protection Factor (SPF): The SPF rating of sunscreen indicates its ability to block ultraviolet (UV)B radiation. Higher SPF values provide greater protection. However, no sunscreen offers 100% protection, and the effectiveness gradually decreases with time.
UV Intensity: Sunscreen effectiveness can be influenced by the intensity of UV radiation. UV radiation is generally stronger at around midday and in regions closer to the equator. It's important to note that UV rays can still reach your skin on cloudy or overcast days.
Water and Sweat Resistance: Water-resistant and sweat-resistant sunscreens can provide extended protection even when exposed to water or during physical activities. However, excessive sweating or water exposure can still diminish their effectiveness, and reapplication is necessary after such events.
Application and Reapplication: Proper and thorough application of sunscreen is crucial for its effectiveness. It should be applied generously to all exposed skin and reapplied at regular intervals as per the product instructions, especially after swimming, sweating, or towel-drying.