As per India Meteorological Department (IMD), India experienced its warmest decade on record spanning from 2014 to 2023. According to a 2020 assessment conducted by the Ministry of Earth Sciences (MoES), the nation has witnessed a notable rise in mean temperatures at a rate of 0.15 degrees Celsius per decade since 1950. 

Despite South India traditionally experiencing fewer heat waves compared to North and Central regions, it is anticipated to encounter abnormal high temperatures in 2024. And to everyone’s surprise, the prediction turned out to be true. Atleast 15 areas in Maharashtra, India, recorded maximum temperatures exceeding 40 degree Celsius (104 degrees Fahrenheit), which is significantly higher than the usual levels for season. 

In the year 2022, Mona Desai, former president of Ahmedabad Medical Association, from Gujarat stated in an interview for Reuters says that “we are getting many patients who have suffered heat stroke or other heat-related problems”. She further added that more than half of the patients were children — an age group particularly vulnerable to extreme heat.

 

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Heat exhaustion is caused by severe heat and the common symptoms include dizziness, lightheadedness, headache, fainting, nausea, vomiting, weakness, sweating. Heat exhaustion can usually be managed with rest, staying in a cool environment, and ensuring proper hydration, including replenishing electrolytes essential for muscle and body function. In contrast, heat stroke is more serious, requiring medical attention, and is often characterised by dry skin, a body temperature exceeding 39.4 degree Celsius (103 degrees Fahrenheit), confusion, and sometimes loss of consciousness.

According to a 2019 research published by the Cambridge researchers, last year (2018) extreme heat left 90 per cent of the country vulnerable to public health risks like heatstroke, food shortages, and even death.

When the body is at rest, it emits heat comparable to a 100-watt light bulb, which is manageable in temperatures below its own 37°C (98.6°F). However, once the surroundings surpass this threshold, the body relies on evaporative cooling, or sweating, to prevent overheating. Capillaries near the skin expand to capitalise on the cooling effect, evident in the flushed appearance signalling the onset of cooling mechanisms. Yet, in high humidity, sweating becomes less effective as the air is already saturated with moisture. Without sufficient evaporation, the blood fails to cool down, leading to a rise in core temperature and the activation of emergency responses to safeguard essential bodily functions.

 

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Is Heat or Humidity Responsible for Heat Waves?

Both in conjunction are responsible but the main culprit is humidity. Humidity influences how the body perceives temperature through a metric known as the apparent temperature. In environments with both soaring temperatures and humidity, despite sweating, moisture fails to evaporate from the skin, diminishing the cooling effect. This leaves the body vulnerable to overheating. This underscores the significance of considering not just temperature alone but the combined impact of heat and humidity on human comfort and health. Also, different regions have varying thresholds for temperature and humidity, impacting mortality rates accordingly.

Another significant factor affecting mortality and morbidity is the evening time temperature. When temperatures stay high overnight, it exacerbates health risks. The body requires a cooling period, and without it, it becomes overwhelmed, leading to increased fatalities.

 

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Should We Drink Cold Water in Summer?

It's generally advisable to avoid drinking extremely cold water in summer, as it can potentially constrict blood vessels and hinder hydration. Also, nerves along the food pipe and stomach can get stimulated when you drink cold water. In the worst cases, when the vagal nerves carrying signals between brain, heart and digestive system get stimulated, it can cause the patient to pass out.

Also, as per Ayurveda, it is believed that consuming cold water or drinks can weaken the digestive fire, known as Agni, and hinder the digestion process. According to Ayurvedic principles, digestion involves a series of processes that require heat, starting from the mouth and ending in the intestines and consuming cold water could disrupt the same. This is the main reason why South Indians prefer drinking lukewarm water after every meal.

The consequences of heat waves are alarming and need immediate action and acknowledgment. Keep reading to know how the human body and health are affected by heat waves.

 

6 Ways Heat Impacts Your Body

Heat Stroke

Heat stroke stands as the most severe consequence of excessive heat exposure. It arises when the body loses its ability to regulate temperature, leading to a swift rise in body heat. In this state, sweating ceases to be effective, rendering the body incapable of cooling down. Left untreated, heat stroke can result in fatalities or irreversible impairment. Certain demographics, such as young children, the elderly, and specific vulnerable groups like individuals with chronic ailments, those with limited financial resources, and outdoor labourers, face heightened susceptibility to heat-related ailments.

 

Fatigue and Weakness 

Due to extreme heat, blood flow to the skin increases and leaves the heart straining. According to research, For every 0.5°C (1°F) rise in core temperature, a typical person’s heartbeat goes up 10 beats per minute, resulting in a racing pulse and a sense of light-headedness.The brain tells the muscles to slow down, causing fatigue

Additionally, the increased blood flow to the skin during extreme heat can also lead to dehydration as the body loses more fluid through sweating. Dehydration further strains the heart as it tries to maintain adequate blood circulation to vital organs while also regulating body temperature.

 

Heart Attack and Stroke

When the core temperature of the body climbs beyond 40°C (104°F), it triggers a cascade of physiological responses that can have severe consequences. As the body struggles to cool down, vital organs such as the liver, kidneys, and brain become increasingly vulnerable to damage. Cells begin to deteriorate rapidly, compromising their ability to function properly. In this heat-stressed state, the cardiovascular system faces immense strain, often leading to a dangerous condition known as heat-induced cardiac arrest.

The heart, already working overtime to pump blood to the skin's surface for cooling, may succumb to exhaustion and fail, plunging the body into a life-threatening crisis.

 

Related story: What to Eat For A Healthy Heart

 

Respiratory Problems 

During intense heat waves, respiratory problems often worsen due to the increased presence of harmful air pollutants. The soaring temperatures contribute to the prolonged presence of pollutants like ozone and particulate matter in the air. These pollutants can irritate the air passages, leading to inflammation and exacerbating symptoms for people with respiratory issues such as asthma or COPD. 

Moreover, the heat can lead to the formation of ground-level ozone, a key component of smog, which poses serious health risks, especially for vulnerable groups like children, the elderly, and those with existing respiratory conditions. Therefore, it's vital to take precautions to minimise exposure to outdoor pollutants and seek medical help if respiratory symptoms deteriorate during extreme heat.

 

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Muscle Weakness and Cramping 

Muscle cramping and weakness are common symptoms of electrolyte imbalances caused by excessive sweating. When you sweat profusely, your body loses important minerals like sodium, potassium, and magnesium, which are essential for proper muscle function. 

Without an adequate balance of electrolytes, muscles may contract involuntarily, leading to painful cramps and weakness. It's important to replenish lost electrolytes by drinking fluids containing electrolytes or consuming foods rich in these minerals to help prevent muscle issues during periods of intense sweating.

 

Kidney Dysfunction 

As the body's core temperature rises above 40°C (104°F) during a heatwave, it triggers a series of physiological responses, including internal inflammation. This inflammation places additional stress on the kidneys, accelerating their dysfunction. 

According to Jason Kai Wei Lee, an expert on the impact of heat on the human body at the Human Potential Translational Research Programme at the NUS Yong Loo Lin School of Medicine in Singapore, kidneys are typically the first organs to succumb to this pressure. When kidney function is compromised, the body's ability to expel accumulated toxins diminishes, resulting in a buildup of harmful substances that can poison the body. This toxic overload subsequently impacts other organs, causing them to progressively deteriorate.

 

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Keeping the above consequences in mind, it is advisable to stay indoors during the extreme heat hours as much as possible. Always try to carry an electrolyte sachet to keep your electrolytes in check and prevent your body from dehydrating.