Heat waves and people: When is it too hot to handle? Explained | Today’s news
Heatwaves paint a grim picture in parts of India: More than 300 cases of heatstroke in Andhra Pradesh in nearly three months; 16 heatstroke deaths in Telangana; exhausted pigeons falling unconscious from the sky, dehydrated eagles scavenging from roadsides; cents of fish dead in the Delhi lake.
What makes heat waves deadly? How much heat can the human body withstand? When does heat stroke occur? Here we explain:
What are heat waves and how dangerous can they be?
The India Meteorological Department (IMD) defines a heat wave as a period of unusually high temperatures compared to what is normally expected in a given area. It can lead to physiological stress and can sometimes cause death.
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While the temperatures at which heat waves are declared vary from place to place, in India a heat wave is declared if the maximum temperature of the station reaches at least 40 °C or more for plains and at least 30 °C or more for mountainous areas.
Heat wave: When the actual maximum temperature ≥ 45’C
Severe heat wave: When the actual maximum temperature ≥47’C
How much heat can the human body withstand?
The National Disaster Management Authority (NDMA) guidelines for heat waves state that if the ambient temperature remains at the same level, it will not harm the human body. 37°C.
“Whenever the ambient temperature rises above 37°C, the human body begins to gain heat from the atmosphere.
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How heat waves kill
An NDMA report released in 2019 claimed that heat waves in India between 1992 and 2015 caused 24,223 deaths in various states.
“Intensive and sustained efforts by all stakeholders resulted in a significant reduction in heat wave deaths from 2040 in 2015 to 1111 in 2016,” the report said.
She added that deaths due to heat waves further reduced to 384 in 2017 and 25 in 2018. Heat waves also killed wild animals, birds, poultry etc. across the country.
Key factors exacerbating the impact of a heat wave
Humidity is one of the important factors that worsen the impact of heat waves. If the humidity is low, people can tolerate fairly extreme temperatures.
But if the humidity is high, a person can suffer from heat stress disorders even if the temperature rises to 37°C, says the NDMA report.
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He explains that high humidity prevents heat from escaping the human body through sweating. “Since high relative humidity leads to slower evaporation of sweat, the efficiency of the human body’s cooling mechanism is reduced,” according to the IMD.
Other factors that can increase the impact of a heat wave are:
Source of information: IMD(Image created with ChatGPT)
Why are hot nights dangerous?
The IMD explains that if the minimum temperature at night is higher than usual, it also goes into maximum temperatures the next day. Maximum temperatures may be reached earlier the next day and may also last longer.
When high day and night temperatures are observed together, they tend to increase heat stress as the human body finds it difficult to recover from the heat of the day during the night hours, says the IMD.
Why cities suffer more: The urban heat island effect
An urban heat island occurs when a city experiences warmer temperatures than surrounding rural or semi-urban areas, or when areas within a city experience warmer temperatures.
Cities such as New Delhi, Ahmedabad, Hyderabad, Mumbai and Pune witnessed extreme temperature events in the summer of 2024, reflecting the increasing intensity of the UHI.
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Causes of the urban heat island effect include urban surface characteristics, greenhouse gas emissions, heat source concentrations, air pollution, population density, and lifestyle factors such as additional cooling requirements and vehicle emissions.
AQI.in further describes the problem: “Cities built mostly of heat-absorbing materials such as asphalt, concrete and metal trap solar radiation throughout the day.”
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“As the evening sets in, this accumulated heat is slowly released, making the urban environment significantly warmer, especially at night,” he added.
This means that heat waves can become deadly not only when temperatures rise, but when the body, city and public systems can no longer cope with the heat.
“Heat can kill in several different ways”
A report published by the Gavi Alliance says: “Heat can kill in several different ways” and the first is dehydration.
As temperatures in India soared to dangerous levels, experts advised people to stay hydrated by drinking plenty of water and taking electrolyte supplements, while avoiding beverages such as tea, coffee, soft drinks and alcohol.
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“If you don’t drink enough water to replace that lost through sweating and urination, the blood starts to thicken, making it more prone to clotting, which increases the risk of heart attack and stroke,” explains Gavi.
Other health effects of heat waves usually include heat cramps, heat exhaustion and/or heat stroke.
According to reports, over 300 suspected heatstroke cases were found in Andhra Pradesh and 16 people died of heatstroke in Telangana.
What is heat stroke and how much heat can people survive?
Heatstroke is a medical emergency caused by overheating of the body. It happens when the body temperature rises to 40 °C (104 °F). This is a potentially fatal condition.
According to NHS UK, heat exhaustion does not usually require immediate medical attention if you can cool down within 30 minutes. If it turns into heatstroke, it should be treated as an emergency.
If not treated immediately, it can cause confusion, dizziness, nausea, seizures, loss of consciousness and organ failure.
Symptoms of heat stroke include:
Information from the Mayo Clinic(Image created with ChatGPT)
How to stay safe from heatstroke: WHO advises
Keep out of heat
> Avoid going outside and doing strenuous activity during the hottest part of the day.
> Stay in the shade. Remember that the perceived temperature in the sun can be 10-15˚C higher.
> Spend 2-3 hours during the day in a cool place.
> Be aware of the dangers of drowning. Never swim alone.
Stay informed about official heat warnings.
Keep your home cool
> Use night air to cool your home by opening windows after dark when the temperature outside is lower than the temperature inside.
> During the day when outside temperatures are higher than inside, close the windows and cover them with blinds or shades to prevent direct sunlight. Turn off as many electrical devices as possible.
> Use electric fans only at temperatures below 40˚C / 104˚F. At temperatures above 40˚C / 104˚F, fans will warm the body.
> If you use air conditioning, set the thermostat to 27˚C / 81˚F and turn on the electric fan – this will make the room feel 4˚C cooler. It can also save up to 70% of your electricity bill for cooling.
> Remember that it can be cooler outside in the shade.
Keep your body cool and hydrated
> Wear light and loose clothing and bedding.
> Take a cool shower or bath.
> Moisten your skin with a damp cloth, spray or damp light clothing.
> Drink water regularly (1 cup of water per hour and at least 2-3 liters per day).
> Regularly visit vulnerable people in your circle – especially people over 65 and people with heart, lung or kidney disease, disabled and living alone.
Protect infants and children
> Never leave children or animals in parked vehicles for any length of time as temperatures can quickly rise dangerously high.
> Avoid direct sun exposure during peak hours, seek shade or stay indoors instead. Shade can > reduce the sensation of heat by more than 10°C.
> Never cover the pram/pram with a dry cloth – it heats up inside the pram. Instead, use a wet, thin cloth and re-moisten as needed to lower the temperature. Combine with a portable fan for even better cooling.
> Dress children in light, loose-fitting clothing that covers their skin, and use wide-brimmed hats, sunglasses, and sunscreen to protect them from the sun’s rays.
