🔍 Key Concepts

• Oxygen-deficient spaces and why normal filtering masks may not work there • Difference between supplying air from a tank vs. filtering existing air • Typical equipment used for confined space entry on ships

💭 Think About

• Ask yourself which device actually brings its own breathable air, instead of trying to clean or filter the air already in the space. • Consider what happens if there are toxic gases AND low oxygen — which options would still fail, even if they can filter dust or fumes? • Think about the kind of respiratory protection required for entering enclosed spaces such as ballast tanks or cargo holds with unknown atmospheres.

✅ Before You Answer

• Identify which options are air-purifying (relying on the air in the compartment) vs. air-supplying (independent of the compartment air). • Remember that in low-oxygen spaces, no amount of filtering can add oxygen to the air — verify which choice avoids this problem. • Recall standard shipboard procedures for enclosed space entry and what type of breathing equipment is approved for that use.