Which breathing system cannot be utilized in an oxygen deficient atmosphere?

Which breathing system cannot be utilized in an oxygen deficient atmosphere?

• A. Supplied air respirator
• B. Rebreather equipment
• C. Air Purification Respirator
• D. Self contained breathing apparatus

Answer: (C)

In an oxygen-deficient atmosphere you must have a breathing system that supplies breathing air with enough oxygen, not rely on the surrounding air. An air-purifying respirator removes contaminants from the air but does not add oxygen; it depends entirely on ambient oxygen to be safe. If the oxygen level is too low, you can’t get enough oxygen through filters alone, so using an air-purifying respirator could lead to hypoxia and loss of consciousness. The other options provide their own source of breathable air: a self-contained breathing apparatus carries its own supply, so it can be used when the surrounding oxygen is depleted; a supplied-air respirator delivers clean, breathable air from an external source; and rebreather equipment recycles and supplements the user’s breathing gas. Because they provide or ensure adequate oxygen, they are suitable in oxygen-deficient environments.

In an oxygen-deficient atmosphere you must have a breathing system that supplies breathing air with enough oxygen, not rely on the surrounding air. An air-purifying respirator removes contaminants from the air but does not add oxygen; it depends entirely on ambient oxygen to be safe. If the oxygen level is too low, you can’t get enough oxygen through filters alone, so using an air-purifying respirator could lead to hypoxia and loss of consciousness.

The other options provide their own source of breathable air: a self-contained breathing apparatus carries its own supply, so it can be used when the surrounding oxygen is depleted; a supplied-air respirator delivers clean, breathable air from an external source; and rebreather equipment recycles and supplements the user’s breathing gas. Because they provide or ensure adequate oxygen, they are suitable in oxygen-deficient environments.