What type of signal must be prepared by the fire boss at the mine entrance at the beginning of a shift?

The fire boss is responsible for ensuring the safety of everyone entering the mine, and one of their key duties is to establish clear communication regarding potential hazards. A danger signal at the beginning of a shift is essential to alert workers about unsafe conditions that could pose a risk to their health and safety. The color red universally signifies danger or immediate hazards, making it the appropriate color for a signal that warns workers of risks. This standard is crucial for maintaining a safe work environment, as it helps ensure that all personnel are alerted to possible dangers before they enter the mine for the shift.