The practical use of electrets in a public health radon remediation campaign

As part of a long-term assessment of domestic radon in Northamptonshire, England, a batch of 50 commercially available electrets was deployed for nearly 1000 exposures, individual exposure periods ranging from one to eight weeks. Responsivity was comparable with that of recently-calibrated Durridge RAD-7 continuously-monitoring equipment. Voltage history analysis indicated mean voltage decay during manufacturers' QA assessment of 0.059 ± 0.026 V day-1, increasing to 0.114 ± 0.073 V day-1 during storage to first use and to 0.204 ± 0.49 V day-1 during inter-deployment storage. At a representative elevated radon concentration of 500 Bq m-3, the resulting perturbation is 3% over a 7-day deployment; at the typical mean Northamptonshire level of 80 Bq m-3 it approaches 22%. Each electret can be used for up to 25 measurements, which makes the technology attractive for organisational use. It is not suited for deployment by individual householders.