Abstract
A 27-yr-old postgraduate student was found lying at the floor of an unsealed underground dry area, where a valve-opened empty cylinder of liquid nitrogen (150 L) was connected to a cap-removed empty Dewar-flask (10 L) via a copper infusion tube. No injury was found externally or internally. There were petechiae in the bilateral conjunctivae and periorbital skin. The dry area, measuring 300 x 130 x 260 cm, had a communication to the basement of the research building by a window measuring 90 x 60 cm in size at 130 cm above the floor. The scene reconstruction and atmosphere gas analysis revealed that the O2 concentration at 60 cm above the base dropped to 12.0% in 3 min and 10 sec, 10.0% in 8 min and 53 sec, 6.0% in 18 min and 40 sec, and 4.2% in 20 min and 28 sec. The primary cause of death was asphyxia by evaporated liquid nitrogen.