How does heat kill? Pune study to track impact on villagers’ bodies, minds for a year

The study builds on the Vadu Health and Demographic Surveillance System, which KEMHRC has operated since 2003. It records every birth, death and migration among about 2.25 lakh people across 70,000 households in 22 villages.

“Few places in India have such a long, complete record of who is living, suffering from illness and dying,” Dr Patil said.

Temperatures in Pune have crossed 41 degrees Celsius this year, with parts of Maharashtra also recording above-normal temperatures. Every summer, villages around Vadu in Shirur taluka of Pune district experience temperatures that can cross 39 degrees Celsius. Researchers said cases of heatstroke and heat stress have been recorded at private and public health facilities, but it is also important to understand how heat affects people’s physical and mental health.

“Does it disrupt their sleep? Does it stop them from working? Does it strain their hearts or affect their mental health? These are among the questions the study will examine,” Dr Patil said.

The methodology involves collecting data at three levels simultaneously. At the village level, weather stations across the 22 villages will record temperature, humidity, rainfall, sunlight and wind every 15 minutes. At the household level, small sensors installed in 400 homes will record indoor temperatures, including in rooms where people live and sleep.

“In many rural homes with tin or concrete roofs, indoor temperatures can remain high long after sunset,” Dr Patil said.

Around 150 adult volunteers will wear smartwatches for three months to track their sleep, step count and heart rate. Field workers will visit every five to seven days to download the data. Volunteers living in homes without reliable electricity will be provided solar chargers. Dr Patil said that since a commercial weather station costs approximately Rs 13 lakh, the CHEERS-Vadu system would use locally developed, low-cost weather stations to collect weather data specific to the area.

Researchers will also focus on illness and mental health. Field researchers will survey 400 households about recent illnesses, including fever, dengue and chikungunya. They will also ask standard questions about low mood, anxiety, stress and wellbeing.

Dr Patil cited a review of 144 studies that found psychiatric hospital admissions rose by almost 10 per cent during heatwaves. “However, in India, there is almost no data on this, and mental illness is rarely discussed in villages,” said Dr Dhiraj Agarwal, Co-investigator.

Researchers will also conduct 15 to 20 in-depth interviews with volunteers, including outdoor workers and farmers.

“Maharashtra and many Indian cities now have heat action plans. Most rely on weather forecasts and hospital records from towns. Village-level data on how heat affects health is largely missing. CHEERS-Vadu aims to fill that gap. Over time, the data can show how much illness and disability heat causes in rural Pune. That will help health departments decide where to send help, when to issue warnings, and who needs protection most,” Dr Patil said.