Which of the following is NOT a category of respirators?

The classification of respirators typically includes categories that are designed to protect users from various airborne contaminants. AIR purifying respirators filter the air to remove harmful particles, gases, or vapors, making them suitable for environments where contaminants exist at lower concentrations. Airline or supplied air respirators provide a safe source of breathing air from a stationary source, crucial for working in environments where air quality is compromised or unknown.

Self-Contained Breathing Apparatus (SCBA) are another important category that provides breathable air in an enclosed system, enabling users to operate in hazardous atmospheres for extended periods.

While gas masks offer respiratory protection, they are generally considered a specific type of AIR purifying respirator designed primarily for military or emergency situations where protection against chemical, biological, and radiological agents is necessary. However, in the context of standard categories used to classify respirators, gas masks do not stand alone as a separate category but rather fall under the broader classification of air purifying respirators.

Therefore, identifying gas masks as a separate category distinct from AIR purifying respirators is what makes it the correct choice for the question regarding which is NOT a recognized category of respirators.