Tertiary blast injuries occur when the body is:

Tertiary blast injuries specifically refer to the injuries sustained when individuals are propelled by the force of an explosion, leading them to impact with solid objects or surfaces. This phenomenon occurs as a result of the blast wave, which can create enough force to throw people into the air, causing them to collide forcefully with other structures, vehicles, or debris.

Understanding this concept is essential for responding to mass-casualty incidents or explosion-related scenarios, as it helps first responders anticipate the types of injuries victims may sustain based on their proximity to the blast and the surrounding environment. The mechanism of injury in this case is not about the immediate effects of the explosion itself or secondary effects such as flying debris; rather, it focuses on the physical displacement of a person due to the blast.

Other options describe different types of injuries. For instance, being in contact with a toxic substance would pertain to chemical exposure rather than a blast injury, while extreme heat could lead to thermal injuries, and being hit by flying debris relates to secondary blast injuries. Each of these options addresses distinct mechanisms of injury that are important for understanding the full scope of trauma associated with explosive events.