Which of the following is true about gas monitoring during sealing?

• A. Gas monitoring procedures during and after sealing must be included
• B. Gas monitoring is not required
• C. Gas monitoring only before sealing
• D. Gas monitoring during sealing only

Answer: (D)

Gas monitoring during sealing is essential because the sealing operation is when conditions can change rapidly as materials are placed and voids are closed. Monitoring at this moment gives immediate readings and alarms, allowing the crew to halt work or boost ventilation if gas levels rise, and to verify the seal is being formed safely. While baseline checks before sealing and ongoing checks after sealing are important in a broader safety program, the critical requirement highlighted here is to have gas monitoring in place throughout the sealing process itself. This focus on the sealing window ensures any gas release or accumulation is detected and controlled when the risk is highest.