What is the SI unit of exposure which measures radiation in air?

The SI unit of exposure that measures radiation in air is Coulombs per kilogram (C/kg). This unit quantifies the amount of ionization produced in air by X-rays or gamma rays. Exposure is defined as the amount of ionization produced in air, and C/kg directly relates to the ionization of air molecules when they interact with radiation.

While the other units mentioned have specific uses in radiation measurement, they do not serve the same purpose as C/kg in the context of measuring exposure. The Sievert (Sv) is used to measure the biological effect of ionizing radiation on human tissue, accounting for the type of radiation and its impact on health. The Rad (rad) and Rem (rem) are older units that were used for measuring absorbed dose and dose equivalent, respectively. However, with the adoption of the SI system, the conversion to Grey (Gy) for absorbed dose and Sievert (Sv) for dose equivalent was established, making C/kg the current standard for measuring exposure specifically in air.