APPENDIX D (Continued)
Blast Injury to Personnel. There are two basic types of blast forces that occur
simultaneously in a detonation blast wave: the direct blast wave overpressure forces and the
indirect blast wind drag forces. As described in FM 8-9/NAVMED P5059/AFJMAN
44-151VIV2V3, the most important blast effects, insofar as production of casualties requiring
medical treatment is concerned, will be those due to the blast wind drag forces. Direct
overpressure effects do not extend out as far from the point of detonation and are frequently
masked by drag force effects. However, direct blast effects can contribute significantly to the
immediate deaths and injuries sustained close to the point of detonation and, therefore, constitute
an important total casualty-producing effect.
Effects of a Blast Wave. When the blast wave acts directly upon a resilient target,
such as the human body, rapid compression and decompression result in transmission of pressure
waves through the tissues. These waves can be quite severe and will result in damage primarily
at junctions between tissues of different densities (bone and muscle) or at the interface between
tissue and air spaces. Lung tissue and the gastrointestinal system, both of which contain air, are
particularly susceptible to injury. The resulting tissue disruptions can lead to severe hemorrhage
or to an air embolism, either of which can be fatal. Perforation of the eardrums is also a
common, but minor, blast injury.
The range of overpressures associated with lethality can be quite variable. It has been
estimated that overpressures as low as 28 psi (1.96 kgf/sq cm) can be lethal, but that survival is
possible with overpressures as high as 38 psi (2.66 kgf/sq cm). Table D-4 summarizes a typical
range of probability of lethality with variation in overpressure.
Peak Overpressure (psi)
1.6 - 2.3
2.3 - 4.0
Injury From a Blast Wave. It is important to have an appreciation of the potential for
human injury. The human body is remarkably resistant to static overpressure, particularly when
compared with rigid structures, such as buildings. Incident pressures considerably lower than
those listed in Table D-4 will cause injuries that are not lethal.