How can you tell if the Protective Breathing Equipment (PBE) runs out of oxygen?

The correct understanding regarding Protective Breathing Equipment (PBE) is that when it runs out of oxygen, it will collapse and deflate. This is a key characteristic of this type of equipment, which is designed to inflate when it contains adequate oxygen and provide a protective breathing environment. As the oxygen supply diminishes, the structure that holds the equipment in place will begin to lose its shape and air, indicating that the oxygen supply is depleted. This physical change signifies to the user that the equipment is no longer functional for safe respiration.

Options that suggest other forms of indications, such as emitting a loud alarm or changing color, do not align with the actual mechanics of PBE. Additionally, the idea that it would be easier to breathe through is misleading, as a deficiency in oxygen supply would actually result in more difficulty breathing, rather than less. Understanding the physical collapse and deflation of the PBE is crucial for safety awareness in emergency situations.