Place markers before the location of contamination at how many meters?

• A. 200 meters
• B. 100 meters
• C. 300 meters
• D. 400 meters

Answer: (A)

Markers are placed a fixed distance in front of the suspected contamination to create a warning boundary that allows your team to observe, report, and retreat if needed without entering the hazard. The distance of 200 meters gives a practical balance: it provides enough lead time to notice the plume, assess the situation, and communicate the boundary, while still keeping you within a manageable range to coordinate movement and decontamination if necessary. Placing markers much closer, like 100 meters, reduces the warning time and increases exposure risk; placing them much farther, like 300 or 400 meters, can push the boundary beyond where you can effectively map and control the approach, potentially delaying response and increasing confusion.