Extreme heat threatens workers’ health: WHO & WMO warn
Extreme heat is rapidly emerging as one of the most significant threats to workers’ health and economic livelihoods globally, with the World Health Organization (WHO) and the World Meteorological Organization (WMO), both Geneva-based UN agencies, releasing a pivotal joint report in August 2025. Drawing on over five decades of scientific research and recent climate data, the report presents a detailed, evidence-based analysis highlighting the multifaceted impacts of rising temperatures on occupational health, productivity, and social equity. It also offers comprehensive recommendations to governments, employers, and workers to mitigate the growing risks posed by workplace heat stress in a warming world.
The rising threat of occupational heat stress in a warming climate
The WHO-WMO report underscores that extreme heat is no longer a localized or seasonal challenge but has become a pervasive societal and occupational hazard affecting billions worldwide. In 2024, global temperatures reached a record 1.55°C above pre-industrial levels, with daytime highs soaring above 40°C—and reaching 50°C in some regions—contributing substantially to heat stress risks. These intense and more frequent heatwaves increasingly affect both outdoor and indoor workers, especially those in physically demanding sectors such as agriculture, construction, and fisheries, where exposure to direct solar and thermal radiation exacerbates physiological strain.
The report reveals a stark productivity decline—between 2 to 3 percent for every degree Celsius the ambient temperature surpasses 20°C. This not only threatens individual livelihoods but poses systemic risks to national economies, particularly in developing countries with large informal workforces and limited social protections..
Health consequences: From heatstroke to chronic disease
In addition to losses from less productivity, the effects of heat stress on health are widespread and serious. Physiological heat strain due to occupational exposures increases the likelihood of acute health conditions such as heat stroke, dehydration, and syncope and chronic health effects such as kidney injury and neurological damage. Vulnerable populations, especially older workers, those with pre-existing illnesses, and individuals with low levels of physiological fitness are at an even greater risk of heat-related morbidity and mortality. The report highlighted troubling trends, such as rising rates of chronic kidney disease associated with heat exposure, and its increasing contribution to global disability-adjusted life years lost due to occupational risk.
Heat exposure also exacerbates health inequalities as groups that experience inequitable conditions of exposure include informal sector workers, agricultural laborers, and populations in low- and middle-income countries where individuals may have limited access to healthcare, cooling infrastructure, and labor rights enforcement.
Economic and social implications of heat stress
Occupational heat stress has major economic and social costs above and beyond health effects on workers. Reduced worker productivity affects agricultural production, construction completion, fish harvest, and other sectors critical to many economies and food security. Increased heat-related illness generates more healthcare costs for beneficiaries with reductions to wages due to absenteeism, creating losses to net incomes and increasing poverty. Poor communities that depend on workers’ income to support families and children suffer reduced cash flow, falling further into poverty.
Further, increasing heat stress contributes or exacerbates global vulnerabilities related to climate change that are aligned with increasingly unequal patterns by increasing and sustaining the financial burden of already excluded and low-income populations. In particular, the informal economy of low-income populations could bring increasing risks to their sustainable livelihoods as informal workers often do not benefit from regulatory protections and have less access to preventive heat stress modification resources.
Strategic framework and recommendations for heat stress mitigation
The latest WHO-WMO report offers a crucial technical framework and policy advice to governments, employers, health professionals, and workers, with recommendations for localized occupational heat action plans specific to climatic circumstances, sectoral vulnerabilities, and workforce demographics. Some of the recommendations concern modified work/rest regimes, shaded and cooled rest areas, hydration access, and heat suitable personal protective equipment.
It is important for medical and occupational health practitioners to implement training on early detection and treatment of heat illnesses to contribute to reduced mortality and morbidity. The development and implementation of heat-health strategies is more culturally sensitive with the involvement of workers’ unions, local authorities, and community based actors.
The report emphasizes the need for innovation, in particular, affordable and scalable technology-based solutions such as wearable heat stress monitors and evaporative cooling clothing. It also argues that research and monitoring need strengthening in order to maintain intervention effectiveness in a changing climate.
Addressing the global challenge: The imperative of urgent and coordinated action
Heat stress affects worker productivity by slowing rates of work, lengthening rest breaks, and lowering production overall. In agriculture and construction, this manifests as lower crop yield, extended project time frames, and diminished income – not only affecting workers but also bottled supply chains affecting local and even global food security. The unfortunate circumstances compound for the most vulnerable and informal workers – not only do they get paid less as work hours become shortened, their impact on leisure time negatively affects their physical and mental performance.
The report demonstrates how heat stress is compounding poverty and inequality. Workers who are spontaneous and contracted without institutional protections or recourse in developing countries are particularly vulnerable to offsetting productivity and earnings. Women and historically first-nation or grouped ethnic based demographics bear the most significant burden. Cautious leaders must capably intervene and mitigate heat related work loss development, not only to ensure economic development but also to ensure social cohesion and – and heat stress becomes a health issue but now as integral of a socioeconomic issue as well (Down To Earth, 2025).
The WHO and WMO responded to these challenges, providing detailed guidance to assist with the design and deployment of occupational heat action plans that are suitable for the local climate, work types, and worker vulnerabilities. They stress the importance of strengthening protections for at-risk workers, especially older workers, workers with chronic illnesses, workers who are more vulnerable in terms of heat-relevant reproductive health, and other high-performing women, during periods of extreme heat.
Most of the recommended policy changes relate to minor changes in work schedules to avoid exposure to qualification hours of extreme heat, provision of shaded or cooled break areas, provision of good access to safe drinking water, and the delivery of training programs for workers and employers to recognize the stages of heat stress and provide early first aid for heat stress injuries. Of course, they recommend innovative low-cost cooling solutions, and low-cost technology options, such as temperature and hydration trackers, to provide scalable and sustainable options.
In particular, all stakeholders are examined as a necessity, with an emphasis on the active role of governments, trade union representatives, employers, and public health representatives, to work collectively to create legally binding occupational health standards, and to create these standards from science. This requires an ongoing commitment to research and surveillance and an adaptive capacity to modify to accommodate changing climate and climate responses.
The WHO-WMO report places the threat of heat stress within the wider context of the United Nations Sustainable Development Goals (SDGs). They have emphasized that there is an integral relationship between the health SDG (SDG3 Good Health and Wellbeing), the decent work/economic growth SDG (SDG8 Decent Work and Economic Growth), and climate action (SDG13 Climate action, for example). The report warns that if immediate global commitments do not take place, then increased workplace exposure to extreme heat will undo decades of progress in health, social inclusion, social stability, and poverty reduction.
The report’s urgent call to action requires urgent policy changes; investment in infrastructure; enforcement of regulatory policies; and international cooperation to ensure the protection of billions of workers. The economic case is also clear; protecting workforces from extreme heat is necessary to maintain productive workforces, economic livelihoods, and social stability.
WHO and WMO’s joint publication is a great achievement and warning that, effective, multi-functional, and evidence-based interventions are needed to mitigate the increasing threats of heat stress for workers globally, so that workers can have their health, dignity, and economic security in the present, and in the future.
