For workers who don’t get to benefit from Japan’s numerous air-conditioned spaces — builders, delivery personnel, farmers and many more besides — even an array of gadgets such as cooling-fan jackets are not necessarily enough to help them persevere through increasingly hot summers. That, in turn, is putting businesses in a tough spot as they try to balance productivity and safety.

One of Japan’s most prominent construction projects, located on an artificial island in Osaka Bay, is a case in point.

Following record high temperatures last summer, in a statement the Kansai branch of the National Federation of Construction Workers’ Unions (Zenkensoren) raised concerns that “there have been frequent cases of people transported to hospital due to heatstroke” at the 2025 Osaka Expo construction site on Yumeshima island. NHK reported eight suspected heatstroke cases at the expo site in the six months through September 2023.