Which two factors affect canister duration?

• A. Humidity and Temperature
• B. Temperature and Exercise rate
• C. Oxygen purity and Pressure
• D. Dive depth

Answer: (B)

The main thing being tested is how the rate at which the scrubber canister is consumed depends on metabolic demand and temperature. When you work harder, your breathing becomes faster and you produce CO2 more quickly, so more gas passes through the canister per minute. That accelerates the use of the absorbent and shortens canister life. Temperature also matters because the CO2 absorption reaction is temperature dependent; higher temperatures speed up the reaction, causing the absorbent to reach its capacity sooner, while cooler conditions slow the process and extend duration. Other factors like humidity or gas purity can influence performance in other ways, but the two most impactful for canister duration are temperature and exercise rate.