Meet Chennai researchers who study heat stress

Studying the vulnerable population

It is a hot and humid Friday in Chennai and beyond. A team of researchers from Chennai have headed to the Marakkanam salt pans in Villupuram district. Team members have fanned out to different sections of the salt pans.

One researcher is collecting urine sample of workers, another is collecting blood, a group is interviewing workers and another set of them is measuring heat with sophisticated instruments.

When the sun goes down they would return to their lab at Sri Ramachandra Institute of Higher Education and Research to document their findings. Once the field evidence is consolidated, analysed, peer-reviewed, the team would work on advocacy. This research is needed to better understand the impact of heat and heatwaves on human health, especially the vulnerable population, to develop effective mitigation strategies and improve public health interventions.

Vidhya Venugopal, professor of Climate Change, Occupational and Environmental Health at Sri Ramachandra Institute of Higher Education and Research, who is leading this team of researchers, says many lesser-known heat-related illnesses often go unrecognised.

As a global expert in heat and health, Vidhya has studied how high temperatures affect kidney, pregnant women and communities among others. While the direct affect of heat stroke is widely acknowledged, kidney ailments and cardiovascular diseases are not commonly associated with heat.

Having worked in the area for the last 16 years, she says they have rich data to show that heat stress poses significant health risks for vulnerable groups.

This summer, their outreach work extended to street vendors in the city. They like to focus more on women, especially as their working conditions are such that they avoid drinking water and this leads to dehydration and other issues, she says.

“We try to reach out to make sure vulnerable communities are not impacted so much by heat. If exposure is less the impact is less,” says the Velachery resident.

Towards the end of this month, the team will be visiting a research practice centre of the institute located on the outskirts of the city to study and sensitise those coming to the outpatient department. After all, heat preparedness should be a 365-day effort.

Collecting data

Professor Vignesh K.S. and his team of researchers from the Occupational Safety and Disaster Risk Management Department of SRM University are waiting for the sun to burn bright. The June 3, 2025 showers in the city forced them to postpone their plans to set up a camp at an industrial location in Thiruvottiyur where they will be collecting data about heat stress.

In April-May, the team completed the field study from Chengalpattu to Pallavaram. Industrial zones, in particular areas classified as “red” (in terms of contribution to global warming) by Tamil Nadu Pollution Control Board have been the focus of the team this year. They have set up camp near an industrial area with all their devices including an exclusive heat stress monitor.

“Heat stress is calculated based on relative humidity, wet-bulb temperature and globe temperature. Through geospatial technology, we cover areas within a one to three kilometre radius of an industry to understand how the community is getting affected. From that buffer we will access and locate a few sample places where heat exposure is high,” says the assistant professor.

Once the field reports are completed, they work on presenting their studies and publishing them in leading science journals.

Vignesh says their reports played a crucial role in Tamil Nadu government formulating a Heat Action Plan (HAP).

“We are also in a capacity to give recommendations at a regional level on actions that need to be taken during heatwaves and other calamities,” says the professor.

Their role does not end with bringing out a report rather they engage with communities. “We do training programmes with local communities that are vulnerable to heat. Many people do not know what is dehydration, heat stroke, especially those working on the highways. We sensitise them as per public health standards,” he adds.

During the pandemic, the department studied air pollutions levels in various neighbourhoods.

“As researchers, we generally focus on pre-disaster which is prevention, mitigation, preparedness and early warning.”

Resettlement sites in sharp focus

Chennai resident Suchismita Goswami, who is currently pursuing her PhD in the University of Copenhagen in Denmark, is carrying out research on the new risks in resettlement sites in Chennai. This work brings her to the city.

Tamil Nadu Urban Habitat Development Board’s resettlement site in Perumbakkam and the AIR resettlement colony in Thiruvottiyur are where her field works are concentrated. These resettlement facilities had been planned to provide safe and secure housing for communities; however today, floods and heat have impacted them socially and economically.

With heatwaves being a big concern for the State Government, Suchismita thinks there should be a special focus on resettlement sites.

“The findings are very particular to the resettlement sites and as a researcher you cannot universalise that,” says Suchismita, who had a stint with the Madras School of Social Work as a faculty.

During fieldwork, she found it particularly challenging to initiate conversations with residents about heat-related stress. “Given Chennai’s high temperatures, heat is often normalised and rarely discussed as a distinct concern. In the process, I came across several findings unique to resettlement sites,” she says.

The resettlement sites severely lack green cover and also experience long hours of power outage in comparison to the rest of the city during summer months.

The resettlement sites are spread across vast tracts of land, and residents have to walk long distances due to the absence of last mile connectivity. They are typically inhabited by the most marginalised groups who cannot afford alternative housing options within the city

The only formal heat-relief measure mentioned by the administration was distribution of electrolyte water at health centres. Residents however have found their own coping mechanisms such as extending the building, closing shops during the afternoon, installing sheds and curtains, and investing in multiple cooling devices.

The closing of shops or covering store fronts to block heat can reduce business visibility and income. These are new forms of risks which affect their health and finances directly, she adds.