North India is reeling under an intense heat wave.
With temperatures in Bihar and Uttar Pradesh brushing 45 degrees Celsius, the Indian Meteorological Department (IMD) has issued a red alert warning in both states.
Health Minister Mansukh Mandaviya, on Tuesday, 20 June, dispatched teams of experts to visit the states and support their administrations in the public health response to the extreme heat.
According to official records, 11 people have died from the heatwave in North India, although the actual numbers are likely to be much higher.
It's not just India. Heat waves have been declared in several countries across the northern hemisphere, including the UK and the US as well.
Places that don't suffer from heat waves have been recording unprecedented temperatures and testing the limits of human tolerance.
So, how does the human body cope with extreme heat? How can you stay safe? Here is everything you need to know about a heat wave.
What Is a Heat Wave?
While there is no universally accepted definition of a heat wave, it is a period of abnormally hot weather that generally lasts more than two days. It can occur with or without humidity.
According to the India Meteorological Department, a heatwave is defined differently for different regions. "It is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal."
What Happens to the Human Body During Extreme Heat
The normal human body temperature is around 98 degrees Fahrenheit which corresponds to 37 degrees Celsius and anything above this is called fever.
In such a scenario, the body is equipped to regulate the temperature and cools itself down.
Dilation of vessels
The most common way is through sweating. "So, this is a body mechanism to lose some amount of water. When the water evaporates, the fluid evaporates from the skin. Then it takes the heat from the body or via convection," Dr Salil Malik, Head - Emergency Medicines at Max Hospital in Gurgaon, said.
The second mechanism is by dilation of blood vessels.
"Basically, the peripheral vessels dilate and this leads to loss of heat from the periphery, so that the body core remains cool," Dr Malik said.
This can be observed in many people, whose cheeks turn red when they feel very hot. So, the skin turns reddish and flushed.
What Are Some of the Heat-Related Illnesses?
When the body is exposed to high temperatures, the process of cooling down can be difficult.
In this kind of a situation, there is sweating and loss of fluids from the body.
"The body tries to retain salts in the initial phase, but as the dehydration increases, there will be decrease in urine output. So, the salts will also be lost in the sweat and because of that there will be dehydration in the body," Dr Malik said.
If this dehydration increases, it can affect the brain, which can lead to symptoms like confusion, agitation and disorientation, he added.
During extreme heat, one can have heat exhaustion and in extreme cases, a heat stroke.
"Heat exhaustion is something that happens if you're in the heat for a longer time, you get dried up and dehydrated, you feel thirsty and you feel fatigue and there is a lot of sweating altogether," Dr Malik said.
With basic management and some fluid intake you can alleviate the symptoms.
However, during heat stroke, a person may have headaches, may be disoriented, agitated, even confused.
"There is excessive fatigue and paradoxically, instead of sweating, there more of hot and dry skin...In extreme cases, you can even lose consciousness," Dr Malik said.
Red flags for heat strokes: Being agitated, disoriented and then instead of sweating, there is dry and hot skin.
Heat stroke is something which is definitely an emergency and which requires immediate treatment.
Other milder forms of heat-related illnesses include heat burns, which may lead to skin irritation and itching. Due to UV damage, there is also darkening of the skin.
If there is lack of personal hygiene, excessive sweating can also lead to fungal infections in the private areas and in the underarms.
Who Is at Greater Risk?
The elderly population and children below 12 years are at higher risk for severe heat-related illnesses, Dr Malik said.
According to the CDC, 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 are at a greater risk.
Which Are the Organs at Risk?
Very high body temperatures may damage the brain or other vital organs.
"So, if there is a lot of dehydration, the water loss can lead to agitation, confusion, etc.," Dr Malik said.
The kidneys are also affected during extreme heat.
"We do get patients who are dehydrated to that extent that the blood flow to the kidney decreases that leads to some kidney injury and rise of creatinine. It can even lead to kidney failure if the patient has a lot of comorbidities and is weak," Dr Malik said.
How Can You Cope With Extreme Heat?
During extreme heat, watch out for symptoms of a heat stroke and other illnesses.
According to Dr Malik, you can follow these steps to cope outside the hospital setting.
Note: When you sponge the body with cool water, maximum amount of heat loss from the body happens when the water evaporates. It is not the cool water per se that extracts the heat. This is why a fan nearby is important for circulation of air.
What Are the Other Ways You Can Beat the Heat?
Put on a sunscreen
A sunscreen, with a minimum 30 SPF should be applied 30 minutes before stepping out.
"It acts only for three to four hours. It's not like you put it in the morning and you can go throughout the day," Dr Malik said. It should thus be applied throughout the day.
Wear loose, cotton clothing
When you're stepping out, cover your body with comfortable clothing, preferably cotton, so that there is good aeration.
Drink lots of water/fluids
It is definitely important that you drink lots of water or fluids.
"Do not wait till the time you feel thirsty to drink something," Dr Malik said.
Elderly should avoid taking walks in the sun
Walks in the early morning or in the evening are preferable because the elderly population are more inclined to have heat-related illnesses. Children should also not go out during extreme heat.
Don't avoid any food. It's a myth!
No, there is no food that cause heat in the body or make you feel hotter.
"This is an external factor. I would not say there is some specific food that you should avoid per se. Every other thing is a myth," Dr Malik said.