Which of the following should not be done with an SCBA inside a contaminated area?

When operating in a contaminated area, safety protocols dictate that an air supply device like a Self-Contained Breathing Apparatus (SCBA) is essential for protection against hazardous substances. Removing the SCBA in such an environment exposes the firefighter to potentially harmful agents, jeopardizing their health and safety.

The SCBA is specifically designed to provide breathable air in environments where the atmosphere is unsafe. Therefore, maintaining the SCBA's integrity and functionality while it's in use is critical. For this reason, other actions like performing maintenance or checking the air supply are typically done outside of a contaminated area, ensuring the equipment is in proper working condition to provide adequate protection. Donning the facepiece is also appropriate, as it is a vital step before entering a hazardous atmosphere.

In this context, taking off the SCBA stands out as the only action that significantly increases risk, as it compromises the firefighter's respiratory protection in a contaminated environment.