What is a major requirement for individuals using self-rescuers underground?

Individuals using self-rescuers underground must be trained in their use to ensure they can effectively utilize this safety equipment in emergency situations. Self-rescuers are devices designed to provide breathable air in the event of a mine emergency, such as a fire or the release of toxic gases. Proper training is essential for users to understand how to operate the equipment correctly, recognize when it is necessary to use, and extend the time they can survive in hazardous conditions.

Training encompasses understanding the device's functionality, learning how to don the equipment swiftly, and knowing the specific circumstances under which it should be deployed. Without adequate training, there may be a significant risk during a crisis, as users might panic or misunderstand how to use the self-rescuer effectively.

The other options, while they may be considered in certain contexts, do not directly relate to the primary safety function of self-rescuers. For example, while being authorized by management and having a communications device might be pertinent to general safety protocols, they do not address the essential need for individuals to be proficient in using the equipment designed for their immediate safety.