Which of the following statements about radiation exposure is FALSE?

• A. increasing distance from a radiation field decreases radiation exposure
• B. increasing shielding from a radiation field decreases radiation exposure
• C. increasing walking speed in a radiation field decreases radiation exposure
• D. increasing time spend in a radiation field decreases radiation exposure

Answer: (D)

Exposure to radiation is about how strong the field is at you and how long you’re in it. The total dose you receive builds up over time, so the dose is proportional to both the dose rate and the time spent in the field. If you increase your distance from the source, the dose rate drops, roughly due to the inverse-square effect, so exposure goes down. Shielding works by absorbing or blocking more of the radiation, also lowering the dose rate reaching you. Moving through the field faster reduces the time you’re exposed, which lowers the total dose because you’re spending less time accumulating exposure. The statement that increasing time spent in a radiation field decreases exposure is not correct—more time increases exposure, not decreases.