Which type of respirator provides an atmosphere-supplying function?

The correct answer identifies that both the Atmosphere-Supplying Respirator (ASR) and the Self-Contained Breathing Apparatus (SCBA) are types of respirators that provide an atmosphere-supplying function.

An Atmosphere-Supplying Respirator is designed to supply clean air from an external source, ensuring that the user can breathe safely in environments where the air quality is compromised. This type of respirator is essential in situations where the atmosphere may contain harmful gases, vapors, or insufficient oxygen levels.

The Self-Contained Breathing Apparatus (SCBA) also falls under this category, as it is a specific type of atmosphere-supplying respirator. An SCBA has its own air supply and is commonly used in firefighting and rescue operations, allowing firefighters to enter hazardous environments while providing a protected supply of breathable air.

In contrast, Air-Purifying Respirators (APR) do not supply fresh air; instead, they filter the air to remove contaminants but rely on the ambient air, which may not be safe to breathe in all situations. Thus, while APRs are important for certain applications, they do not have the atmosphere-supplying capability necessary for operations in unsafe environments.