In which situation is a coal mine considered dangerous?

A coal mine is considered dangerous particularly during sealing operations due to the inherent risks associated with this process. Sealing operations can involve significant hazards such as the risk of gas accumulation, which can lead to explosions or toxic exposure if not managed properly. During these operations, the mine environment may change rapidly and unpredictably, increasing the danger to workers who may not be fully aware of the specific risks involved.

In contrast, when all safety protocols are being followed, workers are fully trained, and maintenance is regularly scheduled, these factors contribute to a safer working environment. Adherence to safety protocols is designed to mitigate risks, training ensures that workers know how to handle hazardous situations, and regular maintenance helps to prevent equipment failure that could lead to accidents. Therefore, the safest conditions are those where these practices are in place, while sealing operations introduce a level of uncertainty and risk that categorizes the mine as dangerous.