An International Intercomparison of Soil Gas Radon and Radon Exhalation Measurements

The Environmental Measurements Laboratory hosted the Sixth International Radon Metrology Programme Intercomparison Test and Workshop (IRMP6) from 12-15 June 1995. Thirty participants representing 24 different institutions from 11 countries attended. Laboratory exercises consisted of {sup 220}Rn and {sup 222}Rn concentration measurements from a source container, and exhalation measurements from a {sup 226}Ra-spiked concrete slab and a {open_quotes}normal{close_quotes} concrete slab. Field exercises included soil gas radon measurements and radon exhalation measurements. In this report, we pooled the participants` data and used the ratio of the standard deviation (SD) to the arithmetic mean, expressed as a percentage, to assess participant agreement for each exercise. For the exhalation measurements from the {sup 226}Ra-spiked slab, this value is 37%; for soil gas {sup 222}Rn, this value is 120%, 36% and 27% for each depth range, 0.4-0.5, 0.6-0.75 and 0.9-1.0 m, respectively; for the surface exhalation measurements, this value is 34%. For the drum {sup 222}Rn measurements, the percent SD after removing a linear trend was 13%. These results indicate that sampling errors are greater than instrument errors. 11 refs., 8 figs., 8 tabs.