Heatwave Condition & Heat Strokes


    In News

    • Recently, eleven people died due to heatstroke in Mumbai.
      • The event brings back the spotlight on potential risks from heat waves, whose intensity and frequency is expected to rise because of climate change.

    What is a heat stroke?

    • Meaning:
      • A heat stroke or sunstroke is the result of overheating of the body as a result of exposure to high temperatures and humidity, or due to prolonged physical exertion at high temperatures. 
      • A heat stroke is considered a medical emergency requiring prompt attention.
    • How?
      • When the body fails to sweat (especially due to high humidity) and is therefore unable to lose heat by evaporation, there is an increase in the core temperature of the body. 
      • If the body fails to cool down, its core temperature can shoot up to 106 degrees Fahrenheit within a few minutes. 
      • This can cause severe health implications including death.
    • Symptoms:
      • Persons suffering from heat exhaustion experience fatigue, dizziness, headache, nausea, vomiting, hypotension (low blood pressure) and tachycardia (increased heart rate).

    Do’s and don’ts while going out in the heat

    • Staying hydrated. Drinking water as often as possible, even if not thirsty.
    • Cover yourself well. Wear lightweight, light-coloured, loose, and porous cotton clothes.
      • Use sunglasses, umbrellas or hats.
      • Use a damp cloth on your head.
    • If you are aware of underlying health issues, avoid standing under the Sun for long.
    • Avoid alcohol, tea, coffee and carbonated soft drinks. They are not a substitute for water. 
    • Avoid high-protein food.

    Government’s recent actions

    • Monitoring and management:
      • Monitoring and management of heatwaves has undergone a big improvement in the past few years and that has resulted in a sharp decline in deaths caused by heatwaves. 
    • Heat action plans:
      • Almost every vulnerable state now has a heat action plan in place, consisting mainly of early warning, provision of water and ORS at public places, and flexible working hours in offices and education institutions. 
      • Special arrangements are made for people working outdoors.
    • Declined deaths:
      • In the 10 years between 2010 and 2020, reported heatwave-related deaths in India came down by more than 90 per cent.
      • Officials say the increase in heatwave-related deaths could also be because of improved monitoring and reporting of incidents.

    What is Heat Wave?

    • It is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season.
    • It typically occurs between March and June, and in some rare cases even extends till July
    • The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

    Criterion for declaring heat waves in India

    • Heat wave is considered if the maximum temperature of a station reaches at least 40°C or more for Plains and at least 30°C or more for Hilly regions.
    • Based on Departure from Normal Heat Wave: Departure from normal is 4.50°C to 6.40°C.
    • Severe Heat Wave: Departure from normal is >6.40 degree C.
    • Based on Actual Maximum Temperature Heat Wave: When actual maximum temperature ≥ 45 degree C. 
    • Severe Heat Wave: When actual maximum temperature ≥47 degree C.
    • If the above criteria met at least in 2 stations in a Meteorological subdivision for at least two consecutive days and it was declared on the second day.


    • The prevalence of extreme temperatures around the world is the result of local factors and also global warming.
    • Scientists have made clear how greenhouse gas (GHG) emissions exacerbate temperatures in the oceans, leading to soaring temperatures. 
    • Anthropogenic GHG emissions are culprit in the current plight from intense weather.
    • Crucially, heatwaves and wildfires are ‘unimaginable’ without human-caused climate change.

    Possibility of intense heatwaves

    • Excessively hot summer:
      • The summer this year is predicted to be excessively hot because of the end of the strong La Nina phase in equatorial Pacific Ocean, something that has a general cooling effect on the earth’s atmosphere. 
    • Possibility of El Nino’s occurrence: 
      • New forecasts suggest that El Nino, which has the opposite impacts of La Nina, is expected to kick in from the May-July period itself, earlier than expected. 
      • El Nino also tends to result in suppression of monsoon rainfall over India. 
    • Shortfall in rain:
      • A shortfall in rains is already being apprehended, which could exacerbate the effects of a hot summer, even though the India Meteorological Department has predicted a normal monsoon.

    Way ahead

    • Population exposure to heat is increasing due to climate change, and this trend will continue. 
    • Globally, extreme temperature events or heat waves are observed to be increasing in their frequency, duration, and magnitude.
    • Heat related deaths can be prevented
      • Relatively simple measures like access to water, ORS, and shade can prevent hundreds of deaths. 
      • But these do not happen on their own. The local administration needs to be vigilant and pro-active. And the implementation needs to be monitored by higher authorities on a daily basis.

    Source: IE