What does the rem unit measure in radiation exposure?

The rem unit is a measure of the biological effect of ionizing radiation on human tissues. Specifically, it quantifies the dose of radiation exposure that accounts for the type of radiation and its potential impact on biological systems. This makes it an important unit for evaluating how much harm radiation can cause to body tissues, especially when different types of radiation (like alpha, beta, and gamma) are involved, as they have varying effects on living cells.

Understanding the rem unit is crucial for ensuring safety in environments where radiation exposure can occur, such as in medical imaging and radiation therapy. By measuring the dose in rems, healthcare professionals can manage and mitigate risks associated with exposure to ensure that it remains within acceptable limits for patient and staff safety.

The other options relate to different aspects of radiation measurement but do not correctly define the function of the rem unit. The intensity of radiation and energy absorbed are measured in different units, such as roentgens or grays, and air exposure typically refers to how much radiation ionizes air, which is also measured differently. Thus, defining the rem as the dose at which body tissues are exposed accurately reflects its role in assessing the potential biological impact of radiation.