<正> The effects of different ambient pressures of 53.99

61.33 and 96.60 kPa on theseverity of blast injury were observed in rats.It was found that when the incident shock wavewas 190.40 kPa in its peak pressure and 10 ms in its duration

both the mortality and the severityof lung injury were progressively increased along with the decrease of the ambient pressure.Themortality rate of the rats in the 6th hour after exposure was 0%

25% and 36.8% and the hem-orrhagic area on the lungs was 63.75+69.01

313.50+357.25 and 653.21+652.25 squaremilimeters when the ambient pressure was 96.60

61.33 and 53.99 kPa respectively.In addi-tion

the lung/body index was 0.93+0.21%

1.31+0.65% and 1.50+0.77% respectively.Itis believed that the decrease of the ambient pressure might decrease the tolerance of the rat to theimpact of blast waves to result in higher mortality and more extensive hemorrhage on the lungs.