A smear is used to measure radiation from what?

• A. Wiping cloth or paper over a surface
• B. Airborne contamination
• C. Dose rate in air
• D. Food contamination

Answer: (A)

Smear testing is about detecting removable surface contamination. By wiping a defined area with a cloth or paper, you collect any radioactive material present on that surface. The material on the wipe is then measured to quantify how much contamination can be removed from the surface, which reflects how contaminated the surface is and how well cleaning has worked. This method focuses on surface residues, not what's in the air, in food, or the general dose rate of the environment. Airborne contamination is assessed with air samplers, dose rate in air with detectors in the air, and food contamination with food samples, so a wipe over a surface is the appropriate way to measure smear contamination.