Which of the following is NOT a type of contamination (RAF)?

• A. Removable
• B. Airborne
• C. Fixed
• D. Shielding

Answer: (D)

Contamination classifications describe how radioactive material is present on a surface or in the air and how easy it is to remove. Removable contamination sits on a surface and can be wiped or rinsed away, making decontamination straightforward. Fixed contamination, on the other hand, is stuck to the surface and resistant to simple cleaning, so it requires more effort to remove or may remain attached. Airborne contamination exists as particles suspended in the air, which can be inhaled and spread through ventilation or filtration controls.

Shielding is not a form of contamination. It’s a protective measure used to reduce exposure by attenuating or blocking radiation between the source and the person. So shielding doesn’t describe how contamination is present or removed; it relates to protection, not contamination state.