Which statement is true regarding monitoring of contaminant concentrations in all places where controlled ventilation is required?

• A. Monitoring and recording the concentration of atmospheric contaminants is required in every place.
• B. Monitoring is only required in the main intake airways.
• C. Monitoring is optional in areas with no gas hazards.
• D. Monitoring is required only at the mine portal.

Answer: (A)

Monitoring the atmosphere in every place where controlled ventilation is required is essential because controlled ventilation is used to manage air quality in each specific zone of the mine. Regular monitoring and recording of contaminant concentrations gives real-time warning of any unsafe conditions and creates a traceable record that the ventilation plan is delivering air that meets safety standards throughout the operation. If monitoring were limited to the main intake airways, hazards could still be present in other zones that rely on that ventilation, going undetected. Areas that seem free of gas hazards can change with production activities or changes in airflow, so monitoring in those areas remains necessary. Monitoring only at the mine portal ignores interior zones where methane, dust, or other contaminants could accumulate, posing risks to workers deeper in the mine. Because it ensures safety across all controlled-ventilation zones and provides accountable records, this broad monitoring requirement is the best approach.