As heat affects workers worldwide, health policies struggle to keep up

In the West African nation Sierra Leone’s capital Freetown, “open markets” are common. Here fruit and vegetable sellers, most of them women, work with little shade and hydration. Nearly 15 of Freetown’s 42 markets are open markets and the heat does not just damage the fruits and vegetables causing an economic loss, but also affects workers’ health. “[The] majority of the women in these markets are exposed to prolonged and extensive heat during the day, which impacts their livelihood and leads to economic losses,” said Eugenia Kargbo, who is a senior heat strategist for Africa with the nonprofit Climate Resilience for All and is working with the community to increase awareness about heat. Workers like those of Freetown’s open markets are among the world’s 2.41 billion workers exposed to excessive heat during their workday, according to an International Labour Organization report. Globally, heat is worsening due to climate change and turning deadly. Climate change has made heat wave conditions 10 times more likely in West Africa, according to an April 2024 study by a team of international climate scientists at the collaborative project World Weather Attribution. While there is an understanding of heat strokes and how deadly they can be, chronic exposure to heat that happens through paid and unpaid work is as serious and can be fatal. It causes disease, worsens existing ones, and is only now being talked about. The World Health Organization is increasingly focusing on the health impacts of climate change, including heat stress on workers, and needs to scale up its response in the coming years. Why workers are so vulnerable What makes workers who are exposed to heat during their workday particularly vulnerable is that they experience environmental heat along with the metabolic heat that is produced naturally in their bodies during manual labor. “With the metabolic heat, this can cause body temperature to rise significantly when tasks are strenuous, even on days when temperatures are mild,” Brenda Jacklitsch, health scientist at the U.S. National Institute for Occupational Safety and Health, told Devex. Jacklitsch added that heat stress could affect indoor workers like those working near hot ovens, furnaces, and equipment, and outdoor workers like farm and construction workers. Many workers like delivery drivers may work in both outdoor and indoor hot environments, including vehicles without efficient air conditioning. There is no particular outside temperature threshold that causes heat stress, as it varies from person to person, according to Vidhya Venugopal, professor of industrial hygiene and country director for India at the National Institute for Health and Care Research. The important thing to remember, she said, is that if the internal temperature of a person that is around 37.8 degree Celsius rises by more than 1°C, then it is not safe for the person. “Heat is the silent killer and [it’s] taking the lives of half a million lives each year. … The cost of climate action now is so much cheaper than the cost of inaction.” --— Celeste Saulo, secretary-general, World Meteorological Organization The body uses sweating as a cooling mechanism in such a situation. “But when the temperature inside goes beyond 40°C, then that sweating also stops because the thermoregulatory mechanism fails. Then the body is … trying to protect the other organs like your brain, your kidneys, etc., in an attempt to save them, and hence sweating stops,” Venugopal said. She was also involved with the ILO report that draws attention to the impact of heat on the world’s workers. She added that the regular dehydration eventually affects the kidneys as it is the major body part that processes water. While initially the body recovers on rehydration and cooling down, it does not if exposed to heat stress for years. “So after some time, repetitive kidney insults or injuries slowly start to progress toward a reduction in kidney function,” she said. This happened on a large scale following the 2022 soccer World Cup in Qatar where workers who worked under high heat conditions to build stadiums returned back to their home countries like Nepal with damaged kidneys. In addition, Venugopal said a person’s heart needs to work harder and a few years of chronic exposure to heat can lead to hypertension or high blood pressure. A person might also develop respiratory issues as the breathing rate rises while working in heat, and over 90% of the world’s population lives in areas where air pollution levels exceed WHO’s safe limit. A category that often gets limited attention in the conversation are indoor or home-based workers, who tend to be predominantly women. Women — an often overlooked category Chandrapur in the central Indian state of Maharashtra is blazing hot in the summer with temperatures of over 40°C. Here, Malti Sagne explained, women face both indoor and outdoor heat. Women in low- and middle-income countries are often exposed to heat in the kitchen if they use firewood that can substantially raise indoor air temperatures. In Chandrapur, firewood still continues to be used mostly by families who live in poverty. Sagne, who is the convener of Mahila Rajsatta Andolan, a movement anchored by the Resource and Support Centre for Development that works to empower grassroots women leaders across Maharashtra, said that the outdoor heat appears to have worsened in the past 25 years that she has been engaged with the community — with far-reaching consequences. “I … see widespread depression among women as they worry about their future,” Sagne told Devex. Her anecdotal evidence is backed by science. Climate change has made heat waves 45 times more likely in South Asia, according to a May 2024 study by climate scientists at World Weather Attribution. Higher temperatures are also associated with higher rates of mental health issues. Globally, women form the bulk of the world’s home-based workers. Around 57% or 147 million of the world’s 260 million home-based workers are estimated to be women. “If homes lack air conditioning and adequate ventilation, radiant heat sources like ovens could build up heat in the enclosed environment, potentially making it hotter inside than outside,” Jacklitsch said. The lack of running water and proper sanitation facilities can be an added challenge in hydrating for home-based workers. “And for many workers that have hot jobs outside the home, returning to a hot home lacking air conditioning may make it difficult for them to adequately cool down during their time away from work,” she added. Heat is also increasingly being documented to have an impact on maternal health. “Pregnant women are also suffering from extreme heat and in some cases, it leads to miscarriage,” Kargbo said based on what she has witnessed in Freetown that is also backed by a limited but growing body of scientific literature. The wide-ranging climate and health impacts are receiving the attention of WHO. WHO’s focus on health impacts of climate and heat But WHO has not yet made clear what heat-specific policy response it would be recommending in the coming years, even though it has been drawing attention to how heat stress worsens a person’s existing underlying noncommunicable disease, or NCD, like heart disease or diabetes. At the United Nations annual climate conference COP 28 in Dubai last year, WHO’s director for noncommunicable diseases, Bente Mikkelsen, spoke about heat worsening the NCD toll. The climate and health convergence is still nascent, while the real world impact has escalated at a rate that has caught policymakers and governments napping. The United Nations health agency is currently preparing to scale up its response to climate change, including heat. The global health body said in May that the climate impacts on health will be a major focus area in its four-year plan for the years 2025 to 2028. WHO has been an increasingly larger presence at the annual U.N. climate conference COPs in recent years, and organizes its own Global Conferences on Health and Climate Change every two years, which are held alongside the climate COPs. It also supports countries with technical support to cope with climate change through the voluntary Alliance for Transformational Change in Climate and Health. For over a decade, WHO has been working with countries to help them prepare heat action plans that focus on using weather data to alert local authorities and health facilities. It has also partnered with the World Meteorological Organization to form the voluntary Global Heat Health Information Network that brings together scientists and policymakers to improve awareness and response to heat. In April this year this partnership made a push asking countries how they were considering the health risks of extreme heat. “We want a better perspective of how governments around the world are responding to the increasing risks of extreme heat on health,” Joy Shumake-Guillemot, lead of the WMO-WHO Joint Office for Climate and Health, is quoted as saying. “For example, how is new evidence on heat and occupational health, maternal and child health, and mental health being incorporated into preparedness investments and policy at provincial, municipal or national levels?” On the whole, WHO is working to draw attention to the health benefits of reducing global carbon emissions that would also limit heat from worsening in the years ahead. “Heat is the silent killer and [it’s] taking the lives of half a million lives each year,” Celeste Saulo, the secretary-general of WMO, said during the recently concluded World Health Assembly. “The cost of climate action now is so much cheaper than the cost of inaction,” she added. WHO Director-General Tedros Adhanom Ghebreyesus too has emphasized the economic argument to urge countries to respond to increasing extreme weather events like heat waves. “Climate action could save millions of lives each year and generate a return of over 4 US dollars for every dollar spent,” he said earlier this month. In a recent study published in the Journal of Global Health and co-authored by WHO experts, upgrading existing infrastructure, building workforce capacities, and health literacy in communities are some of the key suggestions that are provided as steps for climate action. Yet currently, most health systems do a poor job of capturing heat-related deaths and illnesses. Doctors and health officials are not always equipped to respond appropriately, according to Venugopal. “There are ways that heat illnesses can be diagnosed but some specific training [is] required usually,” she said. Workers need protection immediately There are a range of solutions places like Freetown are experimenting with. Some are simple like increasing awareness about hydration and increasing shade in open market places, Kargbo said. Others include promoting the use of reflective surfaces on the roofs that can be applied to existing roofs and cooling paints. While these solutions benefit home-based workers the most, scaling up is often a challenge for financial reasons. In places like Chandrapur, Sagne said that air coolers are now common in most households, people rehydrate using cooling drinks, and the local industries break for rest during the peak heat hours of the afternoons. Experts are unanimous that workers — both indoors and outdoors — need protection, and that the response to heat has to be proactive given we know that heat waves are set to worsen. “Many jobs are hot jobs, and workers need to be protected. Providing access to water, rest breaks, and shade is important,” said Jacklitsch. In addition, the right protective gear and training supervisors about heat stress and first aid is needed.