What agent does the nurse assume was used in the attack if all victims at the disaster site have breath with an almond odor?

The presence of an almond odor in the breath of victims at a disaster site strongly indicates exposure to cyanide. Cyanide compounds, particularly hydrogen cyanide, are known for their distinct and recognizable odor that resembles that of bitter almonds. This characteristic smell is one of the critical indicators used in the field to identify potential cyanide poisoning.

Cyanide is a highly toxic substance that disrupts the body's ability to utilize oxygen, leading to rapid cellular asphyxiation. In an emergency scenario or a disaster involving chemical agents, recognizing this symptom can be vital for prompt treatment and evacuation of affected individuals.

While other agents listed could cause serious harm, they do not typically exhibit the almond odor associated with cyanide. Chlorine, mustard gas, and carbon monoxide present different clinical signs and might have other distinct smells, but none would specifically align with the presence of an almond aroma indicative of cyanide exposure. Thus, the identification of the almond smell as a key symptom directs intervention strategies and informs responders about the specific chemical threat involved.