1995 Volume 30 Issue 4 Pages 303-308
To obtain the basic data for radon, we carried out the measurement of the 222Rn concentration in outdoor air at Wakasa district (21 measurement points) with a cup monitor for 449 days. From the comparisons between 222Rn concentrations and exposure rates or 226Ra radioactivities in soil, the following conclusions were made.
1. The range of 222Rn concentrations averaged for 449 days were from 12.4Bq/m3 to 1.9Bq/m3. The seasonal variation of 222Rn concentration showed low concentrations from spring to summer.
2. 1Bq/m3 of 222Rn concentration was estimated to contibute to about 0.5nGy/h of exposure rate.
3. The clear correlation between 222Rn concentration and 226Ra radioactivity in soil was observed. From the correlation obtained, the remote source component of 222Rn concentration in outdoor air was estimated to be about 2Bq/m3. 100Bq/kg of 226Ra radioactivity in soil was estimated to produce about 7Bq/m3 of 222Rn concentration in outdoor air through various complex paths from soil.
