exposure. The cumulative effects of the exposures might lead to serious short-term and long-term health impairments (Richmond et al., 1981). For those without body armor, the effects of blast are more deadly, and the whole spectrum of blast injuries can be seen (Table 2.3). Apart from the injuries caused by blast overpressure (primary blast effects), they have an increased potential for penetrating injuries from shrapnel and other debris (secondary blast effects) and for acceleration and deceleration of the body and head (tertiary blast effects) (Figure 2.6). Moreover, although barriers and check points may be used to prevent vehicles and personnel carrying explosives from entering a facility, in urban areas it may not be possible to achieve the recommended standoff distances shown in Table 2.1, and even those distances may not be adequate to prevent BINT injuries.

BASIC MECHANISMS OF EXPLOSIVE INJURIES

Physics

A blast wave generated by an explosion starts with a single pulse of increased air pressure that lasts a few milliseconds. The negative pressure or suction of the blast wave follows the positive wave immediately (Owen-Smith, 1981). The duration of the blast wave—that is, the time that an object in the path of the shock wave is subjected to the pressure effects—depends on the type of explosive and the distance from the point of detonation (Clemedson, 1956). Table 2.1 summarizes the safety zones—that is, the standoff distances—for various types of bomb explosions.

TABLE 2.1 Safety Recommendations for Standoff Distances from Different Types of Exploding Bombs

Container or Vehicle Description

Maximum Explosives Capacity

Lethal Air-Blast Range

Maximum Evacuation Distance

Falling-Glass Hazard

Pipe 2 × 12 in

5–6 lb

 

850 ft (259 m)

 

Pipe 4 × 12 in

20 lb

 

 

 

Pipe 8 × 24 in

120 lb

 

 

 

Bottle 2 L

10 lb

 

 

 

Bottle 2 gal

30 lb

 

 

 

Bottle 5 gal

70 lb

 

 

 

Boxes or shoebox

30 lb

 

 

 

Briefcase or satchel bomb

50 lb

 

1,850 ft

(564 m)

1,250 ft

(381 m)

1-ft3 box

100 lb

 

 

 

Suitcase

225 lb

 

1,850 ft

(564 m)

1,250 ft

(381 m)

Compact sedan

500 lb in trunk

100 ft

(30 m)

1,500 ft

(457 m)

1,250 ft

(381 m)

Full-size sedan

1,000 lb in trunk

125 ft

(38 m)

1,750 ft

(534 m)

1,750 ft

(534 m)

Passenger van or cargo van

4,000 lb

200 ft

(61 m)

2,750 ft

(838 m)

2,750 ft

(838 m)

Small box van

10,000 lb

300 ft

(91 m)

3,750 ft

(1,143 m)

3,750 ft

(1,143 m)

Box van or water or fuel truck

30,000 lb

450 ft

(137 m)

6,500 ft

(1,982 m)

6,500 ft

(1,982 m)

Semitrailer

60,000 lb

600 ft

(183 m)

7,000 ft

(2,134 m)

7,000 ft

(2,134 m)



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