Which description correctly defines an atmosphere-supplying respirator?

Which description correctly defines an atmosphere-supplying respirator?

• A. A respirator that removes contaminants by filtering ambient air
• B. A respirator that relies on negative pressure generated by breathing
• C. A respirator used only in clean environments
• D. A respirator that provides air from a clean area or compressed air

Answer: (D)

Atmosphere-supplying respirators deliver breathing air from a separate source, not from filtering the surrounding air. They provide air from a clean area or from a compressed-air supply, so the wearer is protected even when the ambient environment is contaminated or lacking safe oxygen. That’s exactly what the description in the correct option states, making it the best choice. This differs from an air-purifying respirator, which relies on filtering the air in the surrounding environment. The idea of using negative pressure from breathing describes a common mechanism of some tight-fitting respirators but isn’t the defining feature of an atmosphere-supplying type. And using a respirator only in clean environments defeats the purpose of an atmosphere-supplying device, which is intended for hazardous environments where the ambient air isn’t safe.

Atmosphere-supplying respirators deliver breathing air from a separate source, not from filtering the surrounding air. They provide air from a clean area or from a compressed-air supply, so the wearer is protected even when the ambient environment is contaminated or lacking safe oxygen. That’s exactly what the description in the correct option states, making it the best choice.

This differs from an air-purifying respirator, which relies on filtering the air in the surrounding environment. The idea of using negative pressure from breathing describes a common mechanism of some tight-fitting respirators but isn’t the defining feature of an atmosphere-supplying type. And using a respirator only in clean environments defeats the purpose of an atmosphere-supplying device, which is intended for hazardous environments where the ambient air isn’t safe.