In CPR, the duration of a rescue breath should be described as approximately:

• A. Approximately half a second
• B. Approximately one second
• C. Approximately three seconds
• D. Approximately five seconds

Answer: (B)

The main idea here is delivering a quick, controlled breath that ventilates without stopping chest compressions for too long. A rescue breath should be about one second long—just enough to see the chest rise. This timing provides adequate oxygenation while keeping interruptions to compressions minimal. If the breath lasts only about half a second, the lungs may not fill properly, reducing oxygen delivery. If it lasts three seconds or longer, compressions are paused too long, blood flow to the heart and brain drops, and there’s a higher risk of air entering the stomach. So, about one second is the best description for a rescue breath.