A blast injury is a complex type of physical trauma resulting from direct or indirect exposure to an explosion. Blast injuries range from internal organ injuries, including lung and traumatic brain injury (TBI), to extremity injuries, burns, and hearing and vision injuries. The primary mechanisms involved include:
Primary Blast Injury: This is caused by the supersonic blast wave. The wave compresses gas-filled spaces in the body, such as the lungs, ears, and intestines, which then rapidly re-expand, causing shearing and tearing forces that can damage tissues and perforate organs. Primary blast injuries include:
Blast lung (pulmonary barotrauma)
Tympanic Membrane rupture and middle ear damage
Abdominal hemorrhage and perforation
Globe (eye) rupture
Concussion (mild traumatic brain injury (mTBI) without physical signs of head injury)
Secondary Blast Injury: This occurs when fragments from the explosive device or surrounding environment are propelled at high speeds, causing penetrating injuries. Secondary blast injuries result when strong blast winds behind the pressure front propel fragments and debris against the body and cause blunt force and penetrating injuries including:
Penetrating ballistic (fragmentation or blunt injuries)
Eye penetration
Closed or open brain injuries
Tertiary Blast Injury: This results from the displacement of the body by the blast wind, leading to blunt trauma when the body is thrown against solid objects leading to the same types of blunt force injuries that would occur in a car crash, fall, or building collapse and may include:
Bone fractures
Traumatic amputations
Blunt injuries
Crush injuries
Closed or open brain injuries
Quaternary Blast Injury: These are other injuries resulting from the explosion, such as burns, inhalation of toxic gasses, and crush injuries from collapsed structures resulting from other explosive products (such as heat and light) and exposure to toxic substances from fuels, metals, and gasses.
Burns (flash, partial, and full thickness)
Blindness
Injury or incapacitation from inhaled toxic fumes (breathing problems from dust, smoke, or toxic fumes)
Quinary Blast Injury: This includes injuries caused by post-explosion environmental contaminants, such as radiation, chemical agents, or biological agents.
Chemical burns
Radiation exposure
Viral or bacterial infections
Explosives Categories
There are two categories of explosives: high-order explosives (HE) and low-order explosives (LE). HEs produce a supersonic over-pressurization shock wave and include TNT, C-4, nitroglycerin, dynamite and ammonium nitrate fuel oil. LEs, on the other hand, lack the over-pressurization wave and create a subsonic explosion. Pipe bombs, gunpowder, and pure petroleum-based bombs (Molotov cocktails) are examples of LEs. Because LEs do not create the supersonic over-pressurization shock wave, victims are not affected by a primary shock wave; this is unique to HEs. Victims do, however, experience secondary through quinary blast injuries from both HEs and LEs.
