What is the typical gas concentration not to be exceeded by GB methane in NERZ?

In the context of Queensland Mining Law, the Notified Emergency Risk Zones (NERZ) are established to manage and mitigate methane emissions in mining operations. The typical gas concentration limit for gob (GB) methane in these zones is set at 0.5%. This threshold is crucial for ensuring the safety and health of miners and preventing hazardous situations that could arise from excessive methane buildup.

Setting the concentration limit at 0.5% strikes a balance between operational viability and the need for safety. Exceeding this concentration could lead to increased risks of explosions or other dangerous incidents, which is why stringent monitoring and control measures are implemented in mining operations.

The other concentration levels represented in the options, while relevant to discussions around gas emissions and mine safety, do not align with the established threshold for GB methane in NERZ. Thus, 0.5% is recognized as the critical limit to maintain good practices in mining safety.