How is radiation exposure primarily measured?

Radiation exposure is primarily measured through the amount of electrical charge liberated in air. This method is based on the principle that when ionizing radiation passes through air, it interacts with air molecules and produces ion pairs. The quantity of these ion pairs can be correlated with the amount of radiation exposure, making this measurement a fundamental approach to assessing exposure levels.

This measurement, known as exposure, is typically reported in units of roentgen (R), where 1 R is defined as the quantity of radiation that produces a specific amount of ionization in air. This method provides a direct and practical way to assess immediate radiation levels in various environments, especially in radiation safety practices.

While absorbed dose and biological effects are critical concepts in understanding radiation's impact on materials and living organisms, they do not specifically measure exposure in the same way as the electrical charge liberated in air. Personal dosimeters are devices worn by individuals to track cumulative dose over time, but they are based on principles that stem from various measurement methods, including the very one outlined in this correct answer.