Between hard labor and mild labor, which has the longer breathing time?

Between hard labor and mild labor, which has the longer breathing time?

• A. 15 min
• B. 60 min
• C. 30 min
• D. 45 min

Answer: (C)

Breathing time on an SCBA depends on how hard you’re working. The cylinder has a fixed amount of air, but your air use rate changes with metabolic demand. When you do hard labor, you breathe more rapidly and deeply, so you burn through air much faster and the available time is shorter. With mild labor, air is used more slowly, so you can last longer on the same cylinder. On a standard 30-minute cylinder, mild work typically yields about thirty minutes of usable breathing time, while hard work might drop to around fifteen minutes. Therefore, the longer breathing time occurs with mild labor, about thirty minutes.

Breathing time on an SCBA depends on how hard you’re working. The cylinder has a fixed amount of air, but your air use rate changes with metabolic demand. When you do hard labor, you breathe more rapidly and deeply, so you burn through air much faster and the available time is shorter. With mild labor, air is used more slowly, so you can last longer on the same cylinder. On a standard 30-minute cylinder, mild work typically yields about thirty minutes of usable breathing time, while hard work might drop to around fifteen minutes. Therefore, the longer breathing time occurs with mild labor, about thirty minutes.