On a survey map, what does a circle with a number inside indicate?

• A. Dose rate at 30 cm
• B. Location of air sample
• C. Location of a smear
• D. Step-off pad

Answer: (C)

In radiation survey maps, a circle with a number marks the location where a smear (wipe) sample was taken. The number serves as the sample’s ID, linking that spot on the map to the lab results and the specific area that was tested for removable surface contamination. This symbol helps investigators track exactly where wipe tests were performed and how those results relate to the map’s hotspots. Dose-rate readings at 30 cm are shown differently, often as a numeric value at the measurement point or via color contours; air sample locations and step-off pads have other distinct symbols or labels, so the circle with a number is specifically about smear sampling.