Rem (Sv) is the occupational exposure unit measure for what?

• A. Exposure in air
• B. Absorbed dose
• C. Dose equivalent (occupational exposure)
• D. Activity

Answer: (C)

Rem measures dose equivalent, which estimates the potential biological effect of radiation on a person by combining how much energy is deposited in tissue with how damaging the radiation type is. In the context of occupational exposure, we’re concerned with the overall risk to the worker, not just the amount of radiation in the air or the energy absorbed by a specific material. That’s why rem is used to express dose equivalent for occupational exposure. The modern SI unit is the sievert, and 1 sievert equals 100 rem. The other concepts—exposure in air (historically roentgen), absorbed dose (gray), and activity (becquerel)—describe different things and are not what rem represents.