Lack of heat-related death numbers shows that India is unprepared for the next crisis

In 2000, the estimated number of deaths due to non-optimal temperatures in India was 175,800, which increased to 294,400 in 2021; similarly, the total deaths linked to high temperatures was 105,900 which increased to 155,900 in 2021; deaths linked to low temperatures in 2000 was 72,900 and 143,700 in 2021, as per the Global Burden of Disease.

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) is the largest and most detailed scientific effort ever conducted to quantify levels and trends in health. Led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, it provides estimates of all-cause mortality — deaths by cause, years of life lost and years with disability among others.

A paper led by the Potsdam Institute for Climate Impact Research (PIK) in Germany, published in Nature on June 29 estimated that across low- and middle-income countries, 4.3% of neonatal deaths were associated with non-optimal temperatures. Climate change was responsible for 32% of heat-related neonatal deaths while reducing the respective cold-related burden by 30%.

Climate change has impacted temperature-related neonatal deaths in all countries surveyed, with most pronounced climate-induced losses from increased heat and gains from decreased cold observed in countries in sub-Saharan Africa, the paper said.

Future increases in global mean temperatures are expected to exacerbate the heat-related burden, which calls for ambitious mitigation and adaptation measures to safeguard the health of newborns. The paper indicated that heat-related mortality has increased in India due to climate change with nearly 3200 neonatal deaths per 100,000 associated with non-optimal temperatures.

While certification of a heat wave death is a challenge simply because all deaths are not related to heat strokes alone, experts have repeatedly said that tracking all-cause mortality during extreme heat episodes can easily provide the magnitude of the problem — All-cause mortality data can be availed from municipalities.

Here’s an example: Ahmedabad faced a heat wave in May 2010 when the temperature reached a high of 46.8 degrees C with a substantial increase in mortality. According to an IIPH paper published in March 2014 in Plos One — a peer-reviewed journal, which covers science and medicine — 4,462 all-cause deaths occurred in May 2010 (severe heat wave period), comprising an excess of 1,344 all-cause deaths. This was an estimated 43.1% increase over the 3,118 deaths in the reference period.

“There are two types of heat wave deaths — exertional which is caused when one exerts in direct sunlight and their body heats up. They are not able to cool down by sweating and then they die. Only 10% of heat wave deaths are such exertional deaths. The non-exertional deaths happen among the vulnerable, the old, sick, infants who are not able to cool down even at night, their kidneys and heart start failing following dehydration,” Dileep Mavalankar, head of the Indian Institute of Public Health (IIPH), Gandhinagar had said in May.

“These people may not have access to cooling at home and they can die anywhere, even at home since it’s not related to exertion. These are not categorised as heat strokes and are hence possibly not being counted as heat deaths at all,” Mavalankar said.

“In 2010, in Ahmedabad, there were 800 excess deaths in a week during the heat wave period. Those excess deaths helped us identify the mortality burden of heat. We saw a similar pattern in Nagpur. So, the government must track excess all-cause mortality during extreme heat and make that data available,” added Mavalankar.

Excess death numbers may certainly have been high this unusually hot summer. HT reported on June 22 that at least 58 people have died in Delhi alone due to heatwaves this summer. This is not even an estimation based on reports from all hospitals and covers only heat stroke deaths.

Against a normal of three heatwave days, 10-18 heat wave days were reported in West Rajasthan, Himachal Pradesh, Punjab, Haryana-Chandigarh-Delhi, HP, Uttar Pradesh, Bihar, Jharkhand, Gangetic West Bengal, East Madhya Pradesh, Bihar, Odisha in June as per the India Meteorological Department (IMD).

Similarly, against a normal four to eight heat wave days during April to June, 20 to 38 days of heat wave were recorded in different parts of east, north and central India. Most frequent heat waves (20-38 days) were reported from Rajasthan, MP, Punjab, Haryana, Chandigarh, Delhi, West and East UP and HP, Odisha, West Bengal, Jharkhand, Bihar, Saurashtra and Kutch.

Given these high numbers, the number of heat-related deaths could be higher than official estimates. But, unless cumulative death data is available, interventions may not be deployed at scale.

"Both extreme heat and extreme cold can impact people’s health, and in some cases, can result in deaths. High heat impacts are highest in Africa, South Asia and Southeast Asia, and are often linked to heart diseases, among other causes. This also remains an active area of research, including understanding how air pollution and high heat interact, and the impacts on human health," said Pallavi Pant, Head of Global Health, Health Effects Institute

The Centre for Science and Environment recently flagged that average humidity has increased in all cities making heat episodes worse.

“Assessing the changing trend in heat, relative humidity and land surface temperature along with day and night time temperatures is necessary to develop a comprehensive heat management plan for the urban centres,” Anumita Roychowdhury, executive director, research and advocacy at CSE.

“This is needed to implement emergency measures during heatwaves to protect public health, and also to develop longer-term strategies to mitigate heat by increasing green areas and waterbodies, improving thermal comfort in buildings, and reducing waste heat from vehicles, air conditioners and industries,” she said.