What type of respiratory protection uses a compressed air cylinder with exhaled air vented to the atmosphere?

The correct identification of the respiratory protection that uses a compressed air cylinder with exhaled air vented to the atmosphere is categorized as an open-circuit Self-Contained Breathing Apparatus (SCBA). In this system, the user breathes in oxygen from the compressed air cylinder, and once exhaled, the air is released into the atmosphere. This allows the user to have a fresh supply of air for inhalation and then safely vent the exhaled air, preventing any buildup of carbon dioxide within the breathing apparatus.

In contrast, other types of respiratory protection, such as closed-circuit SCBAs, recycle exhaled air by removing carbon dioxide and replenishing oxygen. Half-mask and full-face respirators do not utilize compressed air cylinders but instead often rely on filters that can become saturated and require regular replacement, and they do not vent exhaled air in the same manner as an open-circuit SCBA. Thus, the definition of the open-circuit system aligns perfectly with the mechanics of venting exhaled air, confirming it as the correct response.