bleach, refine, expose, air
曝 centers on exposing something to the elements, especially sunlight or air, to change it: bleaching, airing out, or refining by open exposure.
曝 combines 日 (sun) with 暴, which likely contributes both sound and the idea of exposing or laying open. The character suggests exposing something to sunlight.
The sun 日 on the left shines on the right side 暴, like laying something out in the open under strong sunlight to bleach or air it.
For バク, imagine bleaching a white cloth in the sun and then backing away: back -> バク, as you leave the cloth exposed to the light.
being exposed to radiation; radiation exposure
to expose to the wind; to dry (something) in the wind
low level radiation; low dose irradiation; low dose exposure
internal exposure (to radiation)
external exposure (to radiation)
radiation exposure
to weather (e.g. by long exposure to sun or rain); to lose color; to decay
airing of books
aeration
airing of clothes, hanging scrolls, etc. (to prevent damage from insects and mould)
person exposed to a harmful amount of radiation (from a bomb, industrial disaster, lab experiment, etc.)