CHENNAI: Even as Tamil Nadu reels under one of its harshest summer heat spells in recent years, with temperatures consistently breaching the 40-degree Celsius mark across several districts, a new peer-reviewed study has warned that climate change-driven heat stress significantly affects the productivity, health and livelihoods of outdoor workers in the state.
The study, ‘Quantifying the impact of heat stress on labour productivity in outdoor workplaces in southern India amid a changing climate’, which was published in the journal, ‘Scientific Reports’, found that rising temperatures and prolonged exposure to extreme heat significantly reduced labour productivity among informal outdoor workers, many of whom already labour without adequate social protection or occupational safeguards.
Undertaken between 2021 and 2023 across 11 districts of Tamil Nadu, the study surveyed 1,560 workers employed in agriculture, construction industry, brick kilns, salt pans and stone quarries – occupations that demand prolonged outdoor exposure under intense heat.
The findings revealed that nearly 61% of the workers reported productivity loss during summer, compared to 39% during winter. Further, workers exposed to elevated heat stress faced risk of reduced productivity by as much as 1.4x, while the risk of heat-related illnesses such as dehydration, cramps, headaches, nausea and fatigue more than doubled.
The study was authored by Dr Vidhya Venugopal, country director, NIHR Centre on Environmental Change and Non-Communicable Diseases (NCDs), Sri Ramachandra Institute of Higher Education and Research, along with her students PK Latha and Rekha Shanmugam.
Researchers measured heat stress using the Wet Bulb Globe Temperature (WBGT) index, which factors in temperature, humidity, solar radiation and wind speed. During summer months, WBGT values reached as high as 35°C, well above internationally accepted limits for engaging in hard outdoor labour.
Vidhya said simple policy interventions could substantially reduce the burden on workers. “We operate on one principle: if a policy change, a piece of evidence, or a single finding can make a worker’s day safer or their plate a little fuller, then generating that evidence and pushing for that change is exactly what we’re here for,” she told TNIE. Stating that 80-85% of the country’s workforce is employed in informal sector, the study called for urgent measures, including mandatory work-rest cycles during peak heat hours.