What action is required when a place with controlled ventilation has a GBC of at least 2.5% CH4?

• A. Immediately report to supervisor
• B. Withdraw to a place of safety
• C. Take action to eliminate the danger if competent
• D. Take measures to prevent immediate danger to other coal mine workers

Answer: (B)

When methane is detected at or above 2.5% in a place that has controlled ventilation, the immediate action is to withdraw to a place of safety. This threshold signals a significant gas hazard, increasing the risk of ignition or an explosive atmosphere if you stay in the area or try to continue work. Moving to a safe location removes you from the gas-rich zone so you’re protected while gas levels are assessed and the area is re-ventilated or otherwise made safe.

Reporting to a supervisor is important, but the question asks for the required action you take right away. Actions to eliminate the danger or to implement measures to prevent danger to others come after you’re in a safe location and the situation is assessed by competent personnel.