| Summary: | Environmental samples like soil, building materials and decorative materials are the major source of indoor radon. The contribution of these environmental materials toward indoor radon level depend upon the radium content and radon exhalation rates and can be used as a primary index for radon levels in the dwellings. Sealed cup technique was used to determine the radon exhalation rates and the effective radium content in different environmental samples collected from Jazan city, Saudi Arabia.
Back diffusion is the main removal processes of radon from its sealed cup which leads to underestimate the measured parameters. To assure the quality of the measurements, the results were corrected for back diffusion effect and checked for the effect of sample mass on the measured parameters. The combined uncertainty was also calculated taking into consideration the possible sources of uncertainty.
The overall weighted mean of areal exhalation rate (EA) and effective Radium content (Raeff) for soil samples collected from different 10 districts in Jazan city is 17.02 ± 2.06 Bq m−2d−1, 3.01 ± 0.37 Bq kg−1 respectively. For 20 Building materials samples, EA = 1.989 ± 1.056 Bq m−2d−1 and Raeff = 0.351 ± 0.186 Bq kg−1. Finally, for decorative materials (23 samples), EA = 1.225 ± 0.136 Bq m−2d−1 and Raeff = 0.427 ± 0.031 Bq kg−1. The maximum values of the measured parameters are found in the soil of scheme 5 and 6 district, red sand (building material) and gypsum (decorative material). As the mass of the sample increase, more and more radon diffused back into the sample and the measured effective radium content is reduced. After correcting the results for back diffusion effect, all masses approximately get the same value of effective radium content and then reduced the uncertainty in the weighted mean.
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