Question 26 QMED04 - Boiler Technician-Watertender

The Correct Answer is A. **Why Option A ("freeze burns and blistering") is correct:** When carbon dioxide (CO2) is released from a high-pressure storage cylinder (as in a fire extinguisher or fixed suppression system), it undergoes rapid expansion. This rapid expansion causes a significant drop in temperature, a process known as adiabatic cooling. The CO2 quickly turns into solid dry ice (with a temperature of about $-78.5^\circ \text{C}$ or $-109.3^\circ \text{F}$) or a mixture of dry ice and very cold gas. Direct contact with this extremely cold CO2 stream, or the nozzle/horn of the extinguisher, can cause severe cold-induced injuries, commonly known as "freeze burns" or "cold burns," leading to tissue damage and blistering similar to thermal burns. **Why the other options are incorrect:** * **B) undulation:** Undulation means a wavy or rolling motion. This term has no relevance to the hazards or physiological effects of using CO2 as a firefighting medium. * **C) hallucinations:** While exposure to high concentrations of CO2 can cause symptoms like dizziness, confusion, and loss of consciousness (due to asphyxiation and hypercapnia—excess CO2 in the blood), it is not typically known to be a direct cause of hallucinations in the context of fire suppression use. The primary acute physiological dangers are asphyxiation and cold injury. * **D) carbon monoxide poisoning:** Carbon monoxide (CO) poisoning is caused by inhaling CO, which is a toxic gas primarily produced by incomplete combustion (the fire itself). CO2 is a different molecule and does not break down or convert into CO under normal fire suppression conditions. While CO is often a severe danger in a fire environment, it is not a direct hazard caused by the release of the CO2 firefighting agent itself.