Which control is designed to reduce radiation exposure by acting as a barrier between the source and person?

• A. Shielding
• B. Distance
• C. Time
• D. Monitoring

Answer: (A)

Shielding works by placing a barrier of material between the radiation source and the person, absorbing or scattering the radiation so fewer rays or particles reach the operator. The effectiveness depends on the radiation type and the material and thickness used; dense materials like lead or concrete are common for protecting against gamma or X-ray radiation, and the barrier is designed based on attenuation (often described by concepts like the half-value layer). This protection is a physical block, different from increasing distance (which uses the inverse-square law to reduce exposure) or reducing time (which lowers the dose by shortening exposure duration). In practice, shielding is used to protect workers during procedures or in areas with ionizing radiation by maintaining a barrier between the source and people.