Emergency Preparedness Response Course (EPRC) Practice Test 2025 - Free Emergency Preparedness Response Practice Questions and Study Guide

In a scenario where over 20 people developed cough and difficulty breathing after working together, the most likely agent is chlorine gas. Chlorine is a well-known respiratory irritant and can cause symptoms such as coughing, difficulty breathing, and throat irritation. These symptoms are consistent with exposure to chlorine gas, especially in a confined space where multiple individuals are present.

Chlorine gas is commonly encountered in industrial settings and can be released accidentally, leading to rapid health effects on people nearby. In contrast, agents like sarin and cyanide are fast-acting nerve agents that would typically produce more severe symptoms, such as convulsions or loss of consciousness, rather than just respiratory issues. Ricin, on the other hand, is a potent toxin that requires ingestion or inhalation in large quantities to produce serious illness, and while it can cause respiratory symptoms if aerosolized, it is less likely to be responsible in this specific scenario involving a group of people exposed simultaneously.

Thus, chlorine gas is the most appropriate choice due to its known effects and the context provided in the scenario.