What is the CH4 limit for people withdrawing from the area?

• A. People Withdraw 2.0%
• B. People Withdraw 1.5%
• C. People Withdraw 2.5%
• D. People Withdraw 2.2%

Answer: (A)

Gas management in mines uses fixed methane levels to decide when workers can move through an area. For someone withdrawing from an area, the methane concentration in the air must be at or below 2.0%. This provides a safety margin because methane becomes explosive only above about 5% in air, so staying at or below 2.0% keeps the environment well outside the flammable range while workers are leaving. If readings are higher than 2.0%, procedures would require additional ventilation, precautionary controls, or delaying withdrawal until the gas level drops. The other numbers aren’t the standard withdrawal limit, so 2.0% is the correct threshold.