In this work, a novel approach to deduce the release of the natural radioactive noble gas ²²²Rn from solid sources containing the isotope ²²⁶Ra is presented. Therein, supporting radioactivity measurements of the source are used in conjunction with a theoretical description of the dynamics. For radiation protection and environmental research, reliable and comparable ²²²Rn measurements, and therefore reference atmospheres of ²²²Rn, are needed. This work improves their realization.