Which symptom indicates potential exposure to a chemical agent?

Shortness of breath is a key symptom that can indicate potential exposure to a chemical agent. Chemical agents often target the respiratory system, leading to respiratory distress that manifests as difficulty breathing or a feeling of shortness of breath. This symptom can occur due to a variety of chemical agents, such as nerve agents or choking agents, which affect the respiratory system by causing bronchoconstriction, pulmonary edema, or other harmful effects.

While extreme fatigue, severe itching, and muscle spasms can be symptoms of various medical conditions or reactions, they are not specifically indicative of chemical exposure as clearly as shortness of breath is. In the context of potential chemical exposure, shortness of breath directly suggests that the agent may be affecting respiration, making it a critical symptom to recognize for immediate response and treatment.