Climate change is making Japan's summers increasingly hot and humid, and a study has found that labor productivity is falling sharply as a result. Last year, extreme heat in Japan was estimated to have erased 43 hours of work per worker annually, or roughly 2.9 billion hours nationwide.
On Friday, the Nihon Keizai Shimbun (Nikkei) reported that an analysis of the climate in major world cities from 2020 through last year, based on data from the U.S. National Oceanic and Atmospheric Administration (NOAA), showed that Tokyo's highest temperatures and humidity in July and August were similar to those of Bangkok, Thailand, and Singapore.
In hot and humid environments, regulating body temperature becomes more difficult, raising the likelihood of reduced work efficiency.
The Lancet, a British international academic journal, estimated the hours of productivity lost to extreme heat based on labor intensity by industry and the number of workers, and calculated that Japanese workers lost 43 hours per person annually last year.
That amounts to more than five days based on an eight-hour workday, and translates to 2,890,082,000 fewer work hours annually across all Japanese workers. It is also more than double the average annual loss of 1,427,710,000 hours during the 2010s.
Labor losses from extreme heat are not a problem for Japan alone. In China, where many workers are employed in agriculture and construction, the annual loss per person reached 96 hours in 2024, twice that of Japan, and the potential economic losses from extreme heat were estimated at 1 trillion dollars worldwide.
As countries introduce work-restriction rules to reduce the damage from extreme heat, Japan also revised its Industrial Safety and Health Regulations last year. Under the change, employers in job categories at risk of heatstroke are now required to establish reporting systems and emergency response procedures for heatstroke incidents and to widely inform workers of them.
However, according to figures from Japan's Ministry of Health, Labour and Welfare, there were 1,681 heatstroke casualties at industrial sites last year, a 40% increase from the previous year. That is the highest figure since the related statistics began being compiled in 2005.
