“I have felt dizzy many times while working outside this summer,” said Arjun Kumar, a young construction worker from Bihar, while applying wet cement on the fence wall of a two-storey villa in Madgaon, Goa. The ambient temperature on this sunny June day was 33°C, but the real feel was 4 degrees higher due to humidity.

Sweating profusely, Kumar pointed to a nearby clump of trees. “I take breaks in the shade when I feel exhausted, and drink more water. The wind and sweating helps me cool down.”

Around 18 km north at the primary health centre in Cortalim, Goa, patients turned up throughout the summer with symptoms similar to ones Kumar experienced. Most common were dizziness, headaches, high blood pressure, heat rashes and signs of dehydration.

The treatment is straightforward. Doctors check vital signs, administer fluids, cool the patient if needed and monitor recovery.

“Through our experience, we understand when a patient is suffering due to heat,” said the medical officer at the centre, who spoke on the condition of anonymity. “But there is no separate treatment for heat-related illnesses. We treat according to the symptoms the patients show.”

This is a broader challenge facing India’s public health system as temperatures continue to climb. While hospitals and clinics across the country routinely manage patients whose conditions may have been triggered or worsened by heat exposure, multiple experts told CarbonCopy that there is still no comprehensive picture of the country's heat-related disease burden. Nor are there widely adopted clinical protocols to identify, document and treat heat illness as a distinct category beyond the most severe cases.

In fact, former WHO chief scientist Dr Soumya Swaminathan has been advocating the need for a heat commission in India.

Heat is increasingly recognised as a public health threat, yet many of its impacts remain under-reported, behind diagnoses of dehydration, high blood pressure, kidney injury or other common conditions.

“There is a lack of evidence on heat and health. Public health data has to improve,” said Dr Naveen Puttaswamy, Associate Professor of Public Health, SRIHER.

The biggest gap lies in linking illness with local heat exposure. This absence of systematic attribution means medical researchers often lack the information needed to formulate solutions for tackling an increasing health hazard in India. According to this study, there are reportedly 3,400 excess deaths in India every day due to extreme heat.

Improving those datasets would be the first step in improving India’s preparedness to tackle the growing health crisis that is affecting the nation’s 1.47 billion people, say experts.

Cursory Treatment

At the Cortalim health centre, which sees around 100 patients in its outpatient department each day, most people affected by heat are ones working outdoors like painters, electricians, and construction and dock crews.

The symptoms are rarely dramatic. Heat boils, prickly heat, headaches and dehydration are common. Severe cases like acute dehydration and heat strokes are referred to larger hospitals.

The difficulty lies in determining causation, the medical officer told CarbonCopy. A patient with elevated blood pressure may have spent hours working under the sun, but they may also have pre-existing hypertension. Someone complaining of headaches could be dehydrated because of heat exposure or because of another illness altogether.

“A lot of these symptoms are common symptoms,” said the officer. “They might be caused by heat, or by underlying conditions, medical history or age.”

Doctors at Hospicio District Hospital in Madgaon described a similar picture.

A rotational junior doctor working in the general medicine ward said they had treated around five patients with heat-related illnesses during May, most presenting with dehydration-induced headaches that improved with fluid replacement.

Dr Abner, a junior surgeon at the hospital, said severe cases remain relatively uncommon but pointed to another gap: formal education. “There is no structured, theoretical way to treat heat-related illnesses,” he said. “It is not part of the curriculum.”

The hospital's casualty department sees the more serious end of the spectrum. Doctors there have treated patients who had lost consciousness after prolonged exposure to heat, alongside cases involving heat burns and extensive rashes.

The response follows standard emergency procedures rather than a dedicated heat protocol. Staff first assess temperature, blood pressure, pulse, oxygen saturation and blood sugar. Cooling measures include placing wet cloths on the body and positioning patients in front of fans, while intravenous fluids are administered where required before transferring to the ward for observation.

However, these measures are general, and not engineered specifically for heat, according to Dr Puttaswamy.

“A person suffering from both diarrhea and heat will be put on rehydration protocol. That is an important policy gap. The ICMR [Indian Council of Medical Research] should have a protocol for treating people with heat-related illness,” he said.

Information Gap

Besides specialised medical protocols, health records rarely capture details about the built environment surrounding patients, such as ventilation, construction materials or green cover.

According to Dr Puttaswamy, effects of heat are often assumed to be universal. In reality, heat vulnerability is localised and individual. It is influenced by geography, occupation and physiology. Human beings possess natural mechanisms to cope with heat through sweating and acclimatisation, but only up to a point.

“The human body can regulate body temperature through sweating only up to a certain threshold,” he said.

Acute effects are relatively well recognised. Construction workers spending long hours outdoors without adequate rest or hydration may develop dehydration, vomiting or dizziness. Heat stroke can become life-threatening if body temperature rises uncontrollably. The longer-term consequences are far less certain.

Researchers are investigating whether repeated exposure to heat stress contributes to chronic kidney disease, cardiovascular illness or neurological disorders. In parts of northern Telangana and West Bengal, for instance, scientists are examining clusters of kidney disease that coincide with regions experiencing both high temperatures and humidity. But evidence for these links in India remains incomplete, according to Puttaswamy.

“Heat is considered a risk factor for cardiovascular disease. But epidemiological evidence from India is still missing,” he said.

He is equally concerned about children growing up in overheated homes. Indoor temperatures can exceed outdoor conditions by several degrees when buildings trap heat, particularly in densely built urban neighbourhoods with poor ventilation.

“If this continues, there could be impacts such as stunted growth, developmental delays and disorders, but we need evidence,” Dr Puttaswamy told CarbonCopy.

In fact, heat affects children more than adults because they have a higher surface area to body mass ratio, which absorbs more heat, according to Dr. Garima Sharma, a paediatrician based in Faridabad, NCR, where temperatures reached up to 45 degrees Celsius this summer.

“Children have a high metabolic rate because of growth spurts, and hence generate more heat in comparison to adults. They are unable to recognise thirst urges and delay fluid or water intake. This leads to loss of electrolytes and more impact of heat,” she said.

Inaccurate Measurements

Part of the challenge lies in how heat itself is measured as well.

Weather forecasts and heat advisories generally rely on ambient air temperature recorded about two metres above ground. But multiple experts told CarbonCopy that this often fails to capture how conditions are experienced by the human body. Humidity, wind, direct sunlight and reflected radiation all influence physiological stress.

Humid conditions can be particularly dangerous because perspiration no longer evaporates efficiently, according to Abhiyant Tiwari, Lead of Health & Climate Resilience at NRDC India.

“In dry heat, if you get shade and airflow, perspiration cools the body. In humid heat, the sweat does not evaporate, so that cooling effect is lost,” he explained.

This hampers the human body’s ability to regulate heat. When this happens over a longer period of time, the body redirects blood from internal organs to the skin to dissipate heat. Combined with high internal temperature, water loss due to excessive sweating, organs like the kidneys and the heart start getting affected.

Qutubuddin, a construction worker in Benaulim, Goa, who had suffered from kidney stones earlier, told CarbonCopy that his kidneys hurt more during the summer months. “If I have to work outdoors during summer, I work in two shifts — from 6 AM to noon, and then again from 4-6 PM.”

High night-time temperatures present another concern. The body cools down overnight — or it is supposed to. When nighttime temperatures remain high, that physiological recovery does not happen.

If the body is unable to cool after the sun sets, cumulative physiological strain can build over successive days, said Tiwari.

“The cumulative ripple effect of continuous high temperature puts the body under strain. This has mental health impacts, and studies have linked high night time temperatures to higher domestic violence and violence. There’s a cognitive impact which negatively affects studying and working performance,” said Tiwari. “If your body does not cool down, you get sleep deprived.”

Another construction worker in Navelim, Goa, said that hot nights really impacted his ability to sleep and work the next day. He relied on frequent cold showers and coffee to power through the day.

If the body is unable to cool after the sun sets, cumulative physiological strain can build over successive days, said Tiwari. “In case of direct heat exposure, people with co-morbidites or chronic diseases find it difficult to maintain the thermal regulation,” he said.

The result of it is a cascade of health outcomes: kidney disorders, renal disease, deteriorating heart conditions, according to Vishwas Chitale, Fellow, Climate Resilience at CEEW. The cumulative exhaustion shows up the next morning as reduced productivity and, over days, as a medical emergency, he explained.

The Wet Bulb Globe Temperature, or WBGT, which incorporates humidity and radiant heat alongside ambient temperature, is a better measure for measuring how heat impacts the human body, according to all the experts interviewed.

Data-led Policies

Dr. Yogindra Samant, Occupational Safety and Health Specialist at the International Labour Organization (ILO), told CarbonCopy that several countries have incorporated heat stress assessment tools such as the Wet Bulb Globe Temperature (WBGT) index into occupational safety and health guidance and workplace heat management programmes. These tools can help employers assess heat exposure risks and implement appropriate preventive measures for workers exposed to high temperatures.

He noted that the most effective heat stress interventions focus on reducing exposure before relying on individual protective measures. “Practical measures may include adjusting work schedules during the hottest parts of the day, rotating physically demanding tasks among workers, providing adequate rest breaks, access to drinking water and shaded recovery areas, and organizing work in ways that limit prolonged exposure to excessive heat," he said.

A number of local administrations in India have also introduced innovative approaches to managing heat risks, according to him. “Ahmedabad’s Heat Action Plan identifies outdoor workers, including construction workers and street vendors, as particularly vulnerable to extreme heat. Measures under the plan include heat early-warning systems, improved access to drinking water and shaded areas, public awareness campaigns, and strengthened health system preparedness to respond to heat-related illnesses,” said Dr Samant.

“Better data on heat-related illness, particularly among outdoor and informal workers, would help strengthen prevention efforts. This includes improved reporting, surveillance and integration of health, weather and workplace information systems,” he said.

These measures would be complemented by stronger heat-health surveillance, better integration of weather and health data, and more consistent reporting of heat-related illness and deaths, according to NRDC’s Tiwari.

“Protocols should shift from reacting to heat emergencies to anticipating risk and enabling early action. There should be better training and preparedness across healthcare facilities. Heat should be integrated into everyday public health practice, not treated as an exceptional event,” he said.

Dr. Puttaswamy argued that reference values developed from Western countries may not adequately reflect India's diverse climates and populations. Developing locally relevant physiological thresholds will require extensive research involving people living in deserts, coastal areas, mountain regions and rapidly urbanising cities.

Without that evidence, doctors will continue treating heat as a collection of symptoms rather than as a broader public health challenge.

As of now, treatment can cool the patient, replace lost fluids and stabilise vital signs. But across health centres and emergency wards, doctors are seeing more illnesses and conditions where heat may not be the sole cause. However, it can become the factor that pushes vulnerable bodies beyond their limits.

Predicting and preventing that is the challenge. Better data can bridge that gap.

Additional inputs by Paridhi Choudhary

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