• In view of the heatwaves during summer, the National Human Rights Commission (NHRC) has asked the 11 states to take immediate pre-emptive measures to protect the vulnerable people especially economically weaker sections who are at risk due to the lack of adequate shelter and resources.

• The NHRC highlighted data from the National Crime Records Bureau (NCRB) about the reported deaths of 3,798 persons between 2018 to 2022 due to heat and sun strokes, and emphasised the urgent need for integrated and inclusive measures.

• The NHRC, in its letter sent to chief secretaries of Punjab, Haryana, Uttar Pradesh, Bihar, Jharkhand, West Bengal, Odisha, Andhra Pradesh, Telangana, Maharashtra, and Rajasthan called for provisioning of shelters, supply of relief material, amendment of working hours and availability of standard procedures for treating heat-related illnesses.

What is a heatwave?

• Higher daily peak temperatures and longer, more intense heatwaves are becoming increasingly frequent globally due to climate change. India too is feeling the impact of climate change in terms of increased instances of heatwaves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heatwave casualties.

• Heatwaves do not fetch as much public attention as more dramatic disasters such as earthquakes and floods, but until more recently they were taking a substantial toll of lives in India.

• A heatwave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season. 

• Heatwaves typically occur between March and June, and in some rare cases even extend till July. 

• The extreme temperatures and resultant atmospheric conditions adversely affect people as they cause physiological stress, sometimes resulting in death.

The IMD has given the following criteria for heatwaves:

i) Heatwave is considered if maximum temperature of a station reaches at least 40°C or more for plains and at least 30°C or more for hilly regions.

ii) When normal maximum temperature of a station is less than or equal to 40°C heatwave departure from normal is 5°C to 6°C severe heatwave departure from normal is 7°C or more.

iii) When normal maximum temperature of a station is more than 40°C heatwave departure from normal is 4°C to 5°C severe heatwave departure from normal is 6°C or more.

iv) When actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, heatwaves should be declared. 

• Heatwaves amplify many risks, such as health-related or economic risks, including increased human mortality, drought and water quality, wildfire and smoke, power shortages and agricultural losses.  

• The health impact of heatwaves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.

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