Federal Emergency Management Agency (FEMA) Standardized Awareness Practice Test

Which correctly describes positive blast pressure?

1. Causes intense internal damage

2. Creates a vacuum or suction effect

3. Is responsible for smoke generation

4. Has no significant impact on structures

The correct answer is: Causes intense internal damage

Positive blast pressure refers to the initial force exerted by an explosive detonation, which causes a rapid increase in air pressure in the vicinity of the blast. This intense pressure wave can lead to significant structural damage and internal injuries. The nature of this pressure wave results in a compressive force that impacts buildings and other structures, often leading to the shattering of windows, collapse of walls, and severe injury to individuals located nearby. While the other options touch on related phenomena that might occur in the aftermath of an explosion, they do not accurately define the immediate impact of positive blast pressure. For instance, the vacuum effect described in another option pertains to the negative phase or the backblast that follows the initial pressure wave. Smoke generation is primarily a result of combustion and not a direct characteristic of positive blast pressure itself. Lastly, indicating that positive blast pressure has no significant impact on structures is misleading, as this pressure is precisely what leads to severe structural failure and damage. Consequently, recognizing the destructive capacity of positive blast pressure is crucial for understanding its implications in disaster response and building resilience.