Research summary of the EMPIR MetroRADON project.

In this paper, a comprehensive overview on the achievements and generated research results beyond the state-of-the-art is given based on the working structure of the joint metrology research project MetroRADON. The results of the project have been targeted at the implementation of the European Council Directive 2013/59/EURATOM on radiation protection (EU BSS) and benefit European and international standards on radon monitoring, radon measurement and calibration, geographical radon mapping, and guidelines on radiological protection, construction products, radiation instrumentation and nuclear data. • Traceable calibration of radon (222Rn) instruments at low activity concentrations. • Reducing the influence of thoron, temperature, and humidity on radon measurements. • Comprehensive study on existing radon measurement procedures in Europe. • "Geogenic Radon Hazard Index" (GRHI) - development of a new tool for radon mapping. • Calibration and measurement procedures for radon concentration in air. [ABSTRACT FROM AUTHOR]