Understanding the Dangers of Heatwaves: Effects and Risk Factors | Max Hospital

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Understanding Heatwaves: Their Effects on the Body and Who is at Risk

By Dr. Kapil Jain in Neurosciences

Jun 10 , 2024 | 5 min read

Understanding Heatwaves

A heatwave, an atmospheric phenomenon characterised by high temperatures and prolonged discomfort, is more than just a meteorological occurrence. It's a force that transforms daily life, tests public health systems, and emphasises the importance of climate action. A heatwave, defined as a persistent period of extremely high temperatures, poses major threats to human health, infrastructure, and ecosystems. 

A heatwave is a prolonged period of unbearable heat that is higher than usual and can significantly influence society. Understanding the characteristics and effects of heatwaves is essential to effectively planning for and responding to them and safeguarding public health.

Causes of Heatwaves

Heatwaves are caused by human activity and climatic conditions that frequently result in extended hot periods. Understanding these factors is essential to reducing their effects and protecting communities.

  • Atmospheric Conditions: Heatwaves can develop when high-pressure systems stall over a region. These systems may trap warm air near the Earth's surface and prevent the regular flow of air masses, resulting in extended periods of hot weather.
  • Global Warming: Human activities, such as deforestation, the burning of fossil fuels, and industrial operations, are the leading causes of the long-term rise in Earth's average temperature, affecting the frequency and intensity of heatwaves.
  • Urban Heat Island Effect: High population densities, large expanses of concrete and asphalt surfaces, and limited vegetation all contribute to the absorption and retention of heat in urban areas, which results in localised areas of high temperature. The urban heat island effect has the potential to intensify heatwaves in urban areas.
  • Human Activities: On a smaller scale, local variables such as land use, deforestation, and irrigation techniques may change an area's surface characteristics and contribute to the formation of heatwaves.

Health Risks of Heatwaves

Extreme heat can affect anybody. Heat-related problems occur when our bodies cannot cool down well to maintain a healthy temperature. This can cause severe and fatal health problems. The primary way your body uses it to cool itself is by sweating. However, it takes more than sweat to keep you cool during high temperatures, especially when the humidity is high. Heat illness may occur if your body temperature rises to dangerously high levels.

Heat-Related Illnesses

  • Heat cramps: It is the mildest form of heat illness, consisting of severe muscle cramps and spasms that occur during or after strenuous exertion and sweating in high temperatures.
  • Heat exhaustion: This results from a loss of water and salt in the body and is more severe than heat cramps. Symptoms may include excessive sweating, weakness, nausea, headaches and dizziness. If left untreated, it can lead to heatstroke.
  • Heatstroke: Heatstroke is a severe heat illness in which the body temperature exceeds 104°F (40°C). It happens when the body's temperature-regulating mechanism fails, resulting in potentially fatal consequences like confusion, seizures, and loss of consciousness. Heat stroke needs immediate medical attention.
  • Dehydration: It is a severe heat-related illness caused by overexposure to the sun and inadequate water intake. Early symptoms may include headaches, dry skin, and decreased urine. Severe cases require immediate medical attention.

Causes of Heat-Related Health Problems

Heat-related health issues occur in various ways:

  • A significant increase in body temperature due to heat buildup causes symptoms such as heat exhaustion and, ultimately, heat stroke, a medical emergency.
  • The diversion of blood flow to the skin requires the heart to work harder than usual. The strain on the heart can cause complications for people with a cardiac ailment, such as triggering a heart attack.
  • Increased sweating can cause dehydration if fluid loss is not compensated for by enough drinking. Dehydration can induce weakness and fainting, kidney problems, and worsening of other medical conditions.

Effects of Heatwaves on the Body

Heatwaves can significantly affect human health and well-being. Here are a few effects of heatwaves on humans:

  • Worsening of Chronic Conditions: Heat can worsen chronic conditions such as respiratory, cardiovascular, and kidney diseases by altering the body's normal responses to heat and impairing its capacity to cope with high temperatures.
  • Sleep Disturbances: High night temperatures can interrupt sleep patterns, lowering sleep quality and duration. A lack of sleep may increase stress and affect mental performance.
  • Mental Health Impacts: Heatwaves can increase stress, anxiety, and other mental health conditions. They can also limit interaction with others by keeping individuals indoors to avoid the heat, thus leading to feelings of sadness and isolation.
  • Increased Infection Risk: Higher temperatures and humidity can encourage the growth and spread of pathogens. This includes foodborne illnesses, as bacteria multiply quicker at higher temperatures.
Read more-  Understanding Heatstroke: Causes, Symptoms, and Treatment

Identifying High-Risk Groups

Heatwaves can make everyone uncomfortable. It can affect anyone, but some groups are at higher risk than others. These high-risk groups include:

  • Elderly individuals: Elderly individuals, especially those over 65, face increased heatwave risk due to age-related changes in temperature regulation, decreased thirst sensation, and underlying health conditions or medication-related issues.
  • Children: Infants and young children are more susceptible to heat stress during heatwaves due to their immature thermoregulatory systems and reliance on caregivers. They are less efficient at dissipating heat through sweating and may struggle to recognise heat-related illnesses. Dependence on caregivers for hydration, shade, and supervision also increases vulnerability.
  • Individuals with chronic illness: Chronic illnesses like heart disease, diabetes, and autoimmune conditions are at higher risk during heatwaves due to impaired temperature regulation. Medications to manage these conditions may also affect hydration levels and exacerbate heat sensitivity. Heatwaves can worsen underlying health conditions, leading to complications.
  • Outdoor workers: Outdoor workers in industries like construction, agriculture, landscaping, and transportation face increased risks of heat-related illnesses due to physical exertion, direct sun exposure, and limited access to shade or cooling facilities. Despite occupational health and safety regulations, outdoor workers still face significant risks, necessitating proper hydration, frequent breaks, protective clothing, and acclimatisation programs.

Tips for Heatwave Safety

  • Limit outdoor activities: Avoid outdoor activities during hotter hours and plan activities for cooler times. Wear sunscreen, stay in the shade, or use hats and umbrellas for protection.
  • Stay hydrated: To stay cool during hot weather, drink water regularly, even if you are not thirsty. Hot weather causes you to sweat, and you must restore the lost fluids, or you may overheat. To prevent dehydration, keep a water bottle with you throughout the day.
  • Avoid Caffeinated drinks and alcoholic beverages: Avoid drinking sugary sodas, coffee, energy drinks, alcohol, and other caffeinated drinks, as these might cause dehydration. In a heatwave, that is the last thing you need.
  • Dress appropriately: Wear loose-fitting, light clothing, ideally made of breathable fabrics like linen or cotton. Select colours that help lower your body temperature by reflecting sunlight instead of absorbing it.


Understanding the risks and consequences of heatwaves is essential for ensuring public health. We can reduce the effects of heatwaves by identifying vulnerable groups, understanding the symptoms of heat-related diseases, and implementing preventative steps. Staying well-informed, hydrated, and safe during heatwaves minimises health risks and ensures overall well-being. Be prepared and take proactive measures to reduce the impact of heatwaves on yourself and others around you.