The naturally occurring radionuclide radon (222Rn), together with its radioactive progeny, has been widely used to study atmospheric processes and to test and validate comprehensive global chemical transport models. Being a noble gas, radon is not removed from the atmosphere by dry or wet deposition processes, nor does it become attached to aerosols, and so it is a good tracer for air mass movements. This publication summarizes the findings of a technical meeting jointly sponsored by the IAEA and the World Meteorological Organization, at which experts in the fields of radon exhalation from the ground, radon measurements in air, and atmospheric transport modelling came together to discuss the latest developments. A major focus of the meeting was on moving towards agreed approaches to estimating radon exhalation flux densities, and to improving quality assurance of measurements both of radon exhalation flux densities and of concentrations of radon and radon progeny in the atmosphere.