🔍 Key Concepts

• Oxygen depletion in enclosed or confined spaces • How combustion, oxidation (rusting, curing/drying of coatings), and biological decay use up oxygen • Why all potential sources of oxygen consumption in a compartment must be considered together

💭 Think About

• For each option, ask: does this process chemically consume oxygen from the air inside the compartment? • Think about how a confined space differs from the open deck: what happens if oxygen is used up faster than it can be replaced by fresh air? • Could more than one of these processes be happening at the same time in a poorly ventilated compartment?

✅ Before You Answer

• For each choice, decide yes/no: does this process reduce oxygen concentration? • Recall confined space hazards in ship safety training: which common processes are named as causes of oxygen-deficient atmospheres? • Before choosing, check if there is any single option that safely includes all of the conditions that actually consume oxygen.