The availability of affordable continuous radon monitors opens new opportunities for studying the temporal variations of indoor radon and for more precise exposure estimates based on the actual hours spent in homes and workplaces. These new applications require tests of the monitors characteristics, including their response time. A study of a promising electronic radon monitor with high sensitivity, the RadonEye Plus2, was conducted. It was found that it has excellent linearity up to 3500 Bq/m. A slight deviation from linearity within 12% was observed in the range 3500-7000 Bq/m. The reproducibility of measurements with 36 different RadonEye monitors was within 7%, estimated in the range of linearity.
A dedicated procedure for time response characterization was developed based on exposure to rectangular activity concentration pulses (spikes). It was applied to the RadonEye and three other commercial monitors. The determined characteristic response times of the RadonEye monitor are about 40 min for reaching 50% of the plateau of a rectangular pulse and 90 min for reaching 90%. They are somewhat higher than the corresponding response times of the AlphaE monitor, which are 20 and 60 min, respectively. The response times of the RAD7 monitor in sniff mode are about 3 min for reaching 50% of the plateau and 10 min for reaching 90%. The AlphaGUARD monitor in flow-through mode has the fastest response - it reaches 95% of the plateau in less than 2 min. The monitor AlphaGUARD PQ2000 Pro Rn/Tn is therefore recommended for follow-up of the activity concentration in time response studies of other monitors. It is demonstrated that by exposure to spikes the response function of a monitor can be obtained and used to model its response to variable concentrations.
Overall, the RadonEye’s response is sufficiently fast to follow radon variations even in buildings with active ventilation. This sensitive monitor is suitable for homes and workplaces and can be helpful in the installation and investigation of radon mitigation systems and in studies of the indoor radon dynamics.