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  • Human Rights Research Center

Extreme heat and the threat to the lives of South Asian workers

April 3, 2024

Exposed to a 94-degree Fahrenheit temperature directly under sunlight for hours, Raj fainted on the ground and started vomiting. He was hauling bags of concrete mix and sand on a construction site in downtown Singapore on a Saturday afternoon. Despite feeling weak, as a father of two, Raj had no choice but to keep working in such conditions.[1]

What Raj experienced was heat exhaustion, with symptoms of vomiting, tiredness, dizziness, and headache. Without treatment, it could have developed into heat stroke, becoming at risk of losing consciousness and even death. The trigger is long-time exposure to high temperatures and high humidity. But at what point should humans become concerned about their well-being? Scientists measured the wet-bulb temperature (TW) and found a threshold of TW between 86F and 88F with 100% relative humidity [2]. If exposed to a temperature beyond this threshold for hours, even young and healthy humans cannot cool themselves through sweating, thus increasing the likelihood of heat-related illnesses such as heat exhaustion and heat stroke.

South Asia has been witnessing high TW, and climate change is making extreme TW more likely to happen. A study found South Asia to be one of the regions with the most incidents of daily maximum TW going beyond 31-33 degrees Celsius (87.8-91.4 degrees Fahrenheit) for 1-2 hours [3]. In the same vein, another study revealed that South Asia was the region with the third-highest annual average TW from 1979 to 2019 [2]. The peak of TW is usually observed during the summer monsoon season, and as monsoons become more intensive due to climate change, South Asia is predicted to have a higher risk of extreme TW for hours each day. Another study suggested that, under the business-as-usual emission scenario, parts of South Asia could see TW regularly exceeding 35 degrees Celsius (95 degrees Fahrenheit) by the third quarter of the 21st century [4]. This study is a conservative estimation, as many other studies have already observed TW higher than 95 degrees Fahrenheit in many places in South Asia [5].

While the statistics of morbidity and injury caused by humid heat are poorly documented, some news outlets have reported considerable cases. According to World Weather Attribution, Navi Mumbai, a city in India, reported 13 deaths and about 50-60 injuries due to heat stroke on 16 April 2023 alone [6]. The Guardian reported at least 96 instances of heat-related death in Uttar Pradesh and Bihar, the two most populated states in India, over a span of a few days in June 2023 [7]. Likewise, the New York Times wrote about the higher-than-usual casualties in some hospitals in Uttar Pradesh during days above 109 degrees Fahrenheit and 53% humidity in June 2023 [8].  Long before, according to MIT News, an estimated 3,500 people were killed in Pakistan and India during the summer of 2015 [9]. The Indian National Disaster Management Authority also recorded 24,223 deaths due to heatwaves between 1992 and 2015 [10]. Further, based on a study in Lancet Planetary Health, over 111,000 people died in South Asia because of heat during 2000-2019 [11].

Raj is among millions of low-income South Asian laborers who bear the brunt of increasing humid heat. Low-wage workers, outdoors and indoors alike, are one of the most susceptible populations to heat stress in South Asia. They are tasked with heavy work, continuing for hours in construction sites, factories, farms, airports, and fields where they are exposed to heat with little protection and have limited access to cooling facilities. They cannot forgo their jobs because they count on wages to feed their families, and they cannot afford proper medical care. All they can do is develop a tolerance to the humid heat. Still, the climbing temperature with higher humidity is testing their psychological and physiological limits.

In New Delhi, a 34-year-old mason, Ravinder Kumar, worked 10 hours a day on a construction site slicing marble. In April and May of 2022, when the heatwave ravaged India, Ravinder suffered from fatigue, headaches, and fever after each day’s work. He could not rest well at night as the heat kept radiating from the tin roof of his temporary hut. Feeling exhausted, he had to cut his working time to 8 hours to cope with the heat and continue to make money to support his family. [12] Indoor laborers are no better off than outdoor workers like Raj and Ravinder. Women in South Asia heavily rely on homemade street food and clothes for income, but a survey of 202 women across India, Nepal, and Bangladesh noted that more than 40% were spending less time on their informal jobs because of extreme heat and flooding. Goma Daji, a garment worker in Nepal, said that the summer afternoon is too hot to work in her semi-pucca house with a tin roof. She was reluctant to use her fan, worried about the electricity bills. [13]

South Asian countries have announced their adaptive measures in preparation for a hotter future. India launched the Indian Cooling Action Plan in 2019 to address the cooling requirements across sectors and make cooling accessible to all. This plan estimates the cooling demands from residential/commercial buildings, transportation, and supply chain, according to which it makes recommendations on economics, technology, and policies in approach to the goal. [14] Similarly, Bangladesh and Sri Lanka developed the National Cooling Plan in 2018 and the National Cooling Policy in 2021, respectively [15][16]. Pakistan also announced its adoption of a cooling plan in 2026 [12]. If implemented, the three plans/policies could benefit laborers by making air conditioners accessible and by renovating their homes or workplaces with passive cooling technologies. Indeed, these documents highlight the health consequences of extreme heat on vulnerable populations, including low-income laborers. However, many financial and technological concerns are midway to achieving those countries’ cooling objectives in the near future.

Some countries have published national or regional action plans to build resilience against heat waves, providing guidelines beyond the expansion of cooling systems. India is a typical example. It brought the awareness of heatwaves to national attention for the first time in 2016 when it drew up the National Guideline on Heat Wave and finalized it in 2019. In response to the national call, 17 heat-wave-prone states and more than 120 districts/cities from 14 states have prepared their Heat Wave Action Plans to prevent mortalities due to heatwaves. The measures include “rescheduling of working hours for outdoor workers to avoid their exposure to sweltering weather, creation of drinking water kiosks, supply of water through tankers, erection of special shelter homes, increase in health facilities, stocking of ORS (Oral Rehydration Salts) packets at health centers and the nearest Anganwadi centers, placement of cooling systems and construction of gaushalas with fodder banks, etc.” [17] In April 2023, the Ministry of Labour and Employment further urged states and Union territories to undertake mitigation actions such as increasing water supply facilities, ensuring rest areas, and allowing flexible working schedules.[18] Still, all these plans and initiatives have not yet transitioned into regulations. The general labor laws should have defined employers’ obligations to protect their employees from all health hazards, but, unfortunately, heat stress is less emphasized.

The development of cooling technologies and safety assurance in the workforce are indispensable to protect low-income laborers against heat-related illnesses or injuries. While the former will take a longer time to become affordable and accessible to workers, the latter, if enforced, could take effect sooner to reduce workers’ exposure to heat stress. In the US, the Occupational Safety and Health Administration (OSHA) has been drafting a heat-specific workplace standard since 2021. Meanwhile, OSHA has been taking additional actions, launching the National Emphasis Program on heat inspections and ramping up enforcement to ensure employers’ compliance with the general duty clause. [19] Further, California, Colorado, Minnesota, Oregon, and Washington have adopted standards and rules to prevent heat hazards in the workplace. [20] For South Asian countries, initiating a rulemaking process and enhancing the enforcement to align with the current labor laws will be the significant next steps.

More needs to be done to secure and ensure sustainable safety in the workforce. There is growing concern over the increasing electricity prices due to higher electricity demands for cooling, which will further exacerbate the energy poverty of low-income laborers. Meanwhile, the rising energy consumption drives emissions, posing obstacles to the emission reduction objectives. In the long term, a transition to clean energy not only balances energy security and emission control, but also provides new working opportunities. Reskilling and occupational education projects will be necessary by then for workers in industries of phasing-out and unemployed laborers.



Wet-bulb temperature: A wet-bulb measurement is taken by covering a thermometer with a water-soaked cloth. The water evaporating from the cloth, thus lowering the temperature, mirrors how the human body cools down with sweat. The lower temperature in the measurement is the wet-bulb temperature, representing the temperature of the human body after being adjusted by sweating. The closer the wet-bulb temperature approaches the human body temperature at 96.8 degrees Fahrenheit, the more likely humans will be exposed to heat stress. 

National Guideline on Heat Wave: According to the Indian National Disaster Management Authority, “In April 2016, India drew up national guidelines under the title 'Preparation of Action Plan–Prevention and Management of Heat Wave'. The guidelines were twice revised, first in 2017 and then in 2019. They were enriched with recommendations for more specific actions, based on scientific inputs derived from various research papers, reports, and best practices in heat-wave assessment and mapping techniques. The revisions in 2019 included a new section, 'Built Environment'; the revisions focused on short-term, medium-term, and long-term measures for heat-wave risk reduction.”



[1] CNN. (2022, August 2). For Asia’s migrant workers, extreme heat is ‘a matter of life and death’.

[2] Speizer, S., Raymond, C., Ivanovich, C., & Horton, R. M. (2022). Concentrated and Intensifying Humid Heat Extremes in the IPCC AR6 Regions. Geophysical Research Letters, 49(5), e2021GL097261.

[3] Raymond, C., Matthews, T., & Horton, R. M. (2020). The Emergence of Heat and Humidity Too Severe for Human Tolerance. Science Advances, 6(19), eaaw1838.

[4] Im, E.-S., Pal, J. S., & Eltahir, E. A. B. (2017). Deadly Heat Waves Projected in the Densely Populated Agricultural Regions of South Asia. Science Advances, 3(8), e1603322. 

[5] Saeed, F., Schleussner, C., & Ashfaq, M. (2021). Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°c of Global Warming. Geophysical Research Letters, 48(7), e2020GL091191.

[6] World Weather Attribution. (2023, May 17). Extreme humid heat in South Asia in April 2023, largely driven by climate change, detrimental to vulnerable and disadvantaged communities.

[8] Travelli, A., Kumar, H. (2023, June 18). Northern India Endures a Heat Wave, and a Wave of Deaths. The New York Times.

[9] Chandler, D. L. (2017, August 2). Deadly heat waves could hit South Asia this century. MIT News.

[10] Madan, A. (2023, May 6). Understanding the implications and mitigation strategies for heatwaves in India. PreventionWeb.

[11] Hao, Q., Guo, Y., Ye, T., Gasparrini, A., Tong, S., Overcenco, A., Urban, A., Schneider, A., Entezari, A., Vicedo-Cabrera, A. M., Zanobetti, A., Analitis, A., Zeka, A., Tobias, A., Nunes, B., Alahmad, B., Armstrong, B., Forsberg, B., Pan, S.-C., … Li, S. (2021). Global, regional, and national burden of mortality associated with non-optimal ambient temperatures from 2000 to 2019: A three-stage modelling study. The Lancet Planetary Health, 5(7), e415–e425. 

[12] Jha, A., Jain, M. (2022, October 27). South Asia needs equitable cooling as heatwaves worsen. World Bank Blogs.

[13] Nagaraj, A. (2022, January 20). Incomes dip for South Asia's women home workers as heat rises. PreventionWeb.

[14] Ozone Cell, Ministry of Environment, Forest and Climate Change, Government of India. (2019). India Cooling Action Plan.

[15] Ozone Cell, Department of Environment, Ministry of Environment Forest and Climate Change. (2021). Bangladesh National Cooling Plan for the Implementation of the Montreal Protocol.

[16] Ministry of Environment, Sri Lanka. (2021). National Cooling Plan. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/

[17] National Disaster Management Authority, Ministry of Home Affairs, Government of India. (2021). Beating the Heat: How India Successfully Reduced Mortality Due to Heat Waves.

[18] The Times of India. (2023, April 18). Labour Min asks states to takes step to mitigate heat wave effects on workers in different sectors.

[19] Occupational Safety & Health Administration, U.S. Department of Labor. (2023, July 27). Department of Labor Announces Hazard Alert, Steps up Enforcement as Extreme Heat Endangers Workers Across the Nation.

[20] Occupational Safety and Health Administration. 


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