In case of a misfire or suspected misfire, how long must workers wait before returning to the blasting area?

• A. 15 minutes
• B. 30 minutes
• C. 45 minutes
• D. 60 minutes

Answer: (B)

When a blast misfires or is suspected, the priority is to ensure the area is safe before anyone re-enters. Waiting thirty minutes gives time for any delayed initiation to become evident and for potentially dangerous gases to dissipate, reducing the risk to workers. After that wait, a qualified person should inspect the area and authorize re-entry with the proper precautions. Shorter waits, like fifteen minutes, may not cover delayed detonations or gas buildup, while longer waits would unnecessarily slow operations. Thirty minutes is the standard, balanced approach.