Mumbaikars, extreme heat is a big, sweaty drain on your health

MUMBAI: A city usually cradled by the coast, sweltered under brutal heatwave conditions this past week as temperatures brushed 40 degree Celsius, leaving residents battling fatigue, dehydration, and throbbing headaches. But experts warn the real danger lurks beneath the surface. This scorching assault isn't just about sunstrokes.
The World Health Organization (WHO) underlines that exposure to extreme heat can lead to a range of physiological stresses, worsening pre-existing conditions and potentially leading to premature death and disability.Studies have established that infants, pregnant women, new mothers and the elderly face a heightened risk from the extreme heat. According to the annual Lancet Countdown on Health and Climate Change report, heat-related deaths for adults over 65 have increased by 85% since the 1990s.
As climate change claws at our doorstep, experts have called for immediate action. “We need to go beyond tracking heatstroke cases and dehydration--it's time to confront the broader physical and mental health repercussions of a warming world,” said physician Dr Hemant Thacker, who consults with Breach Candy Hospital. Extreme heat impacts various bodily systems, from the brain, heart and kidneys to behavioural and immune functions, cautioned Thacker, adding that excessive sweating can lead to electrolyte pressure which can cause cardiac arrhythmia, mental confusion and dizziness.
A case in point was BJP leader Nitin Gadkari who experienced giddiness and fainted midway through his speech at a campaign rally in Yavatmal last Wednesday. Although he quickly regained consciousness and proceeded with his political engagements, such episodes can have severe repercussions for pregnant women and the elderly. Studies have found associations between extreme heat exposure with low birth weight, preterm birth, and infant mortality, besides heightening chances of dehydration and kidney failure in pregnant women.
In the general population, while the impact of heat on vector-borne diseases such as dengue is widely recognised, there is growing evidence associating extreme heat exposure with strokes and cardiac events. According to cardiologist Dr Ajit Menon, although locally they haven’t witnessed a visible surge in cardiac events during hotter periods, literature strongly suggests the likelihood of such an increase.
If not heart attacks, smaller and persistent health issues are certainly becoming more prevalent in the city. Internal medicine expert Dr Pratit Samdani, who consults at H N Reliance Hospital, has noted a rise in cases of fungal infections, salmonella and gastroenteritis this month. “Sweat trapped in skin folds is leading to fungal infections. Additionally, we're noticing a slight rise in salmonella and gastroenteritis cases, likely due to food spoilage accelerated by the heat or consumption of contaminated water,” he said. In the slum pockets where skin infections are already prevalent due to water scarcity, a further spike is typically seen in summer months, said Dr Shrikala Acharya, a professor of community medicine at KEM Hospital, Parel.
In addition to the physical discomfort, heat is also causing challenges in the realm of mental health. Speaking to Mumbai Mirror at the recent Philanthropy Asia Summit (PAS) in Singapore, Dr Alan Dangour, director of the Climate and Health team at the UK’s Wellcome Trust, highlighted emerging evidence suggesting that extreme heat could impact mental health conditions, and stressed on the urgent need for further research in this area.
Closer to home, Dr Nilesh Shah, head of psychiatry at Sion Hospital, said extreme conditions such as heat, cold and noise are known to provoke irritability and exacerbate stress. However, he believes heat’s broader effects require further investigation.
Globally, experts have been trying to focus on Asia as it ranks among the regions with the highest number of days experiencing dangerously high temperatures. Dr Arunabha Ghosh, founder of Council on Energy, Environment and Water (CEEW), said at the PAS that India is expected to have 20 days of extreme heat this year, a significant increase from the usual average of four or five days. His organisation has created the first heat and humidity hyperlocal action plan for Thane, which gives a neighbourhood-by-neighbourhood weather account for more precise public health intervention.
Dr Dangour said since heat has an impact on health and the risk of death, it also affects productivity and GDP. “In Asia, nearly 25 days a year are potentially lost due to high temperatures, and that has a tremendous impact on the livelihoods of the worker,” he said. Broadly, estimates are that $860 billion were lost in income in 2022 due to heat. “It is important to understand the impacts of heat by gathering evidence to drive the mitigation narrative,” he said.
Monitoring all-cause mortality could serve as one of the reliable methods for detecting any unusual increase in deaths during hotter summer months,” said Dr Dileep Mavalankar, director of the Indian Institute of Public Health in Gandhinagar. He suggests that analysing where these deaths occur, whether at home or outdoors, could offer crucial insights. By tracking excess deaths, a staggering 1,344 additional deaths were revealed in Ahmedabad during May 2010 when a heatwave swept through the city.
On April 16, Mumbai recorded its hottest day in over a decade with temperatures soaring to 39.7 degree Celsius. Now, meteorologists have predicted two more dangerously hot days towards the end of this month, with temperatures expected to exceed 37 degrees. While these heat waves may seem momentary, forecasts suggest they'll become more frequent and severe in the coming years.
Dr Thacker advocated for certain immediate mitigation strategies. For instance, public messaging should stress the importance of drinking water regularly, rather than waiting until dehydration sets in. By afternoon, individuals—especially children, pregnant women, and the elderly—should have consumed several litres of water. Additionally, educating the public on seeking shaded areas, using fans, and opening windows for ventilation is crucial. He added that it is important for healthcare professionals to recognise the correlation between heat and health issues. Thacker advises adjusting the dosage of diuretic medications (causes frequent urination) for the elderly during extreme heat. Additionally, he says pregnant women and elderly should frequently monitor their BP.
“Obesity, 10 years ago, was a condition. Today it’s a disease. Similarly, heat is not a geographical condition, but a clinical threat now,” Thacker said.