The Radon Tracer Method (RTM) is a top-down approach to estimate greenhouse gas emissions. While simple in principle, incorrect use can complicate interpretation of results. Based on observations from a range of contrasting sites, this article reviews the underlying assumptions and key considerations for applying the RTM. It also introduces the concept of coupling RTM analyses with nocturnal stability classification, to reduce uncertainty of fetch estimates and improve interpretation of results.

This paper presents a new user-friendly version of the Atmospheric Radon MONitor (ARMON). The efficiency of the instrument is of 0.0057 s^-1, obtained using different techniques at Spanish and German chambers. The total calculated uncertainty of the ARMON for hourly radon concentrations above 5 Bq m^-3 is lower than 10 % (k = 1). Results confirm that the ARMON is suitable to measure low-level radon activity concentrations and to be used as a transfer standard to calibrate in situ radon monitors.

The automatic and low-maintenance radon flux system Autoflux, completed with environmental soil and atmosphere sensors, has been theoretically and experimentally characterized and calibrated under laboratory conditions to be used as transfer standard for in situ measurements. It will offer for the first time long-term measurements to validate radon flux maps used by the climate and the radiation protection communities for assessing the radon gas emissions in the atmosphere.

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.

There is a growing need in health and climate research for high-quality radon observations. A variety of radon monitors, with different uncertainties, operate across global networks. Better compatibility between the measurements is required. Here we describe a novel, portable two-filter radon monitor with a calibration traceable to the International System of Units, and demonstrate the transfer of a traceable calibration from this instrument to a separate monitor under field conditions.