An approach to creating reference tools for reproducing the units of volumetric activity of radon and thoron and radon flux density from the ground surface based on the physical principles of reproducing these units of quantities, and usage as hardware components of rebuilding bubblers with a radioactive solution of radium salt, reference capacities of a known amount, emanation chambers for generation of thoron, a gamma spectrometer with a semiconducting detector from especially pure germanium, and radon radiometers is featured. The reproduction consists in physically embodying units according to their determination with reference to the formation of radon and thoron in the radioactive radium and thorium series. The proposed approach makes it possible to determine design, structural, and other technical decisions of measurement standards, as well as specific approaches and methods of working with them. The creation of reference tools and technologies for reproducing the units of volumetric activity of radon and thoron and radon flux density from the ground surface makes it possible to ensure unity and reliability of measurements in the field of ionizing radiation, traceability of units, and bringing the characteristics of national standards to correspondence with the level of world achievements.