Primary blast injuries are caused by:

• A. The blast overpressure wave
• B. Flying debris
• C. Ground impact
• D. Thermal burns

Answer: (A)

Primary blast injuries come from the blast overpressure wave produced by an explosion. The sudden, high-pressure pulse travels through the body and tends to injure air-filled organs first, such as the ears (often causing tympanic membrane rupture), lungs (pulmonary barotrauma or air leaks), and portions of the gastrointestinal tract. This mechanism is distinct from other blast injury types: injuries from flying debris arise from secondary projectiles, injuries from being thrown and striking objects come from tertiary effects, and thermal burns stem from heat produced by the blast or ensuing fire. So the overpressure wave itself is responsible for primary blast injuries.