Self-contained breathing apparatus and supplied-air respirators are two types of which category?

• A. Air-purifying respirators
• B. Atmosphere-supplied devices
• C. Self-contained breathing apparatus
• D. Escape respirators

Answer: (B)

The main idea tested is how respirators get their breathing air. Air-purifying respirators filter contaminants from the surrounding air and do not provide a separate air source. Atmosphere-supplied devices, by contrast, deliver breathing air from a source outside the wearer’s immediate environment. Self-contained breathing apparatus carries its air in on-board cylinders, while supplied-air respirators pull air from an external source such as a compressor line or a distant supply. Because both provide air from a source other than the ambient atmosphere, they fit into the atmosphere-supplied category. Escape respirators can be either type, but the umbrella category that covers both SCBA and supplied-air models is atmosphere-supplied devices.