OITA (Kyodo) Police have determined that three workers who died Saturday after collapsing inside an ore ship docked at a smelter in Oita suffocated.
The Oita Prefectural Police made the announcement after inspectors from the Japan Transport Safety Board began an on-site examination of the ship at the facility of Nikko Seiren, a Tokyo-based smelter of nonferrous metals.
The three victims, all employees of a Nikko Seiren subsidiary, lost consciousness and collapsed shortly before 9 a.m. as they entered the ship's hold, which contained about 5,900 tons of copper concentrate. They were confirmed dead after being taken to a hospital.