Sri Lankan fishermen working under a hot sun and strong winds on the coast. Credit: Darsha Seneviratne – Photo: 2025
By Mahinda Seneviratne*
OSAKA, Japan | 8 September 2025 (IDN) — As the sun rose over the picturesque, volcanic mountain region of central Kyushu in Japan, four young women from Myanmar were reporting for work as house maids at a local ryokan (Japanese-style inn). They are part of the growing number of migrant workers evident in the popular tourism and service sectors in Japan, as the demand for foreign labour grows in an ageing population with historically low migration.
Despite an estimated 150 million cross-border migrant workers seeking work that can provide them a higher income than in their home countries, the health & safety of these vulnerable workers has gained attention only recently. The Myanmar women working mainly indoors may be safer than the millions of workers who are required to work outdoors in scorching high temperatures.
The International Commission on Occupational Health (ICOH), the world’s oldest occupational health professional organization, hosted two policy track sessions at the Global Initiative on Safety, Health and Well-Being held at EXPO 2025 in a very sunny Osaka in mid-July. Leading ICOH researchers presented state-of-the-art information on climate change and heat stress among vulnerable workers, especially migrant workers.
Highlighting that 29% of Japan’s population is aged over 65 years, Professor Seichi Horie of the University of Occupational and Environmental Health in Kitakyushu presented data showing a rise in occupational heatstroke and dehydration-related heart disease, indicating that climate change and increasing heat intensity in recent years are affecting Japan’s ageing workforce.
From the Republic of Korea, Professor Jin-Ha Yoon from the Department of Preventive Medicine at Yonsei University in Seoul presented an analysis of a large dataset on heat-related illnesses in his country. His study, which examined differences by occupation and income level, showed that the devastating impact of heatwaves is concentrated on the most socially vulnerable – non-skilled, low-income workers. He emphasized that “the climate crisis is not merely an environmental issue, but an ‘inequality amplifier’ that attacks the weakest links in our society.”
The International Labour Organisation (ILO) has estimated that 70% of the world’s 3.4 billion workers are exposed to excessive heat at work. Most of them are in Africa, West Asia and the Asia-Pacific regions with those in construction, agriculture and transport industry sectors mostly at risk.
Heat-related impacts have been evident for several years among occupations in countries where workers are exposed to high heat daily for most of the year.
Media reports before the World Cup in Qatar in 2022 revealed the large number of migrant workers from South Asia, mostly from Nepal who suffered heat-related illness, injury, or death when living in harsh conditions and working on the construction of several football stadiums for the event.
Meanwhile, the epidemics of chronic kidney disease among sugar cane cutters in several Central American countries and rice farmers in Sri Lanka are lesser known. These cases are also attributed to dehydration at work but other factors including chemical contaminants in drinking water sources are also suspected to be involved.
Professor Vidhya Venugopal from SRIHER, India, whose research on heat stress among Global South workers has revealed alarming findings, exposed the devastating psycho-social toll of climate-induced heat on India’s 139 million migrant workers—23% of the nation’s workforce. Through accounts of migrant women in the informal sector enduring scorching conditions with poverty wages, limited water, no cooling measures, and poor sanitation, Dr. Venugopal emphasized: “The psychological impacts of heat cannot be understood in isolation—they intersect with broader social determinants.” She called for urgent policy reforms and targeted interventions to address this human crisis.
Dr Jason Lee from the National University of Singapore gave a comprehensive overview on the physiological impacts from heat stress that was used in formulating Singapore’s heat stress framework to protect outdoor workers, as shared by Ms Jaime Lim from the Ministry of Manpower. In particular, the combined effects of workload and heat stress on delivery workers servicing the gig economy.
Dr Lee also informed that early this year a new Southeast Asia hub of the Global Heat Health Information Network (GHHIN), a United Nations initiative to protect and prepare for the impacts of heat on human health and well-being was established and hosted by the Heat Resilience and Performance Centre of the university.
This first hub could be a model that can be globally applicable for better awareness raising and practical protective measures on heat stress in other high risk regions. ICOH’s working groups on informal and migrant workers’ health and its scientific committee on thermal factors will collaborate to promote practical guidelines on heat stress for workers in different geographic regions.
Labour hire agencies in source and host countries play a major role in recruiting and supplying migrant workers to potentially vulnerable working conditions in high income countries. This was evident particularly in the Gulf States in West Asia where several migrant workers, supplied under a system operated by unscrupulous migration agents, have died in the past decade from causes related to excessively high heat exposures at work.
Japanese employers are requiring labour supply agencies in source countries to provide Japanese language capability, in addition to job skills training for potential migrant workers several months prior to their first arrival in Japan. This initiative provides a valuable example for other high income countries, where newly arrived migrant workers are often disadvantaged in low skilled, precarious jobs with little or no knowledge of the local language and its cultural norms.
Sri Lankan cleaners in Japan with protective gear. Credit: Mahinda Seneviratne
With growing labour market shortages in many high income countries, the ICOH symposium held at Osaka’s Expo site raised concerns about such workers’ safety and raised the question whether the global demand for migrant labour could provide potentially vulnerable workers with safer work conditions and better health protection when they begin work.
Meanwhile, at the EXPO site in Osaka, a group of newly arrived young Sri Lankans are spending time off from their work in the city’s transport sector, queuing up with the large crowd to view the various exhibition pavilions and displays. Grasping bottles of cool water together with a Japanese language brochure on preventing heat stress, they are seeking a shady spot from the seasonally high Osaka heat.
*Mahinda Seneviratne is a work health specialist practicing in Australia and a Board Member of the International Commission on Occupational Health (ICOH). Views expressed are his own.
AloJapan.com