Written by the Fiveable Content Team โข Last updated September 2025
Written by the Fiveable Content Team โข Last updated September 2025
Definition
Roentgen Equivalent for Man (rem) is a unit of measurement for the dose of ionizing radiation that factors in its effect on human tissue. It accounts for both the energy deposited and the biological impact.
5 Must Know Facts For Your Next Test
1 rem equals 0.01 sieverts (Sv).
The rem takes into account the type of radiation and its biological effects, making it more useful than simple exposure measurements.
It is used to express occupational exposure limits for workers in environments with radiation.
The average annual dose per person from natural background radiation is about 0.3 rem.
Acute health effects such as nausea and fatigue can occur at doses above 100 rem.
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Related terms
Sievert (Sv): A unit measuring the health effect of ionizing radiation, where 1 Sv equals 100 rem.
Gray (Gy): A unit of absorbed radiation dose, where one gray represents the absorption of one joule of radiation energy per kilogram of matter.
Rad: A unit of absorbed dose of ionizing radiation, equal to the absorption of one hundredth of a joule per kilogram (0.01 Gy).