YAMAGUCHI – Police began investigating Thursday an industrial water tunnel in Yamaguchi Prefecture where nine workers were hospitalized the previous day on suspicion of carbon monoxide poisoning.
The Yamaguchi Prefectural Government said none of the workers was in a life-threatening situation, but seven will likely be in hospital for some time.
According to prefectural officials, carbon monoxide filled the tunnel at around 11:30 a.m. Wednesday while the men, aged between 19 and 58, were digging the tunnel floor.
The roughly 15-km-long, 2-meter-high, 2-meter-wide tunnel lies between the cities of Kudamatsu and Shunan.
The fire department said a high-level of carbon monoxide was detected, with rescuers required to wear oxygen masks.
Prefectural officials said water inside the tunnel had been drained and a ventilator was working at the time of the incident.
The 35-year-old president of the subcontractor undertaking the works said he had warned workers to exercise caution after a tunnel worker told him on Tuesday he had detected some kind of gas.
He said the workers who were rescued were “barely conscious” when they got out.