The correlation between indoor and soil gas radon concentrations in Kiraz district, İzmir.

All humans are exposed to radon, the primary source of natural radiation, which can harm people due to natural processes rather than human activity. Thus, it is of significant importance to determine the levels of radon in indoor, soil gas, water, and outdoors. Radon concentration (C) was measured in Kiraz district, İzmir, and the correlation between the indoor and soil gas C values was investigated. The indoor C values measured in 40 randomly selected dwellings in Kiraz exhibited a wide range from 19.50 ± 2.50 to 204.70 ± 8.00 Bq m with an average value of 61.11 ± 4.23 Bq m. The measured indoor C values were compared to the reference levels in the world to help control radon in the dwellings. Indoor C values were lower than the ICRP reference level of 300 Bq m in all of the dwellings studied. Furthermore, in 34 dwellings (representing 85% of the total number of dwellings studied), indoor C values were lower than the WHO reference level of 100 Bq m. Health hazard indices, namely annual effective dose (AED) and excess lifetime cancer risk (ELCR), were also calculated for each dwelling and compared with internationally acceptable levels to estimate the risk to human health. The AED values varied from 0.49 ± 0.06 to 5.16 ± 0.20 mSv y with an average value of 1.54 ± 0.11 mSv y, which exceeds the world average of 1.15 mSv y as reported by UNSCEAR. The ELCR values ranged from 2.05 ± 0.26 × 10 to 21.55 ± 0.84 × 10 with an average value of 6.43 ± 0.44 × 10, exceeding the world average of 0.29 × 10 as reported by UNSCEAR. The soil gas C values measured exhibited a wide variation ranging from 129.25 ± 6.38 Bq m to 6172.64 ± 44.06 Bq m with an average value of 1291.79 ± 18.70 Bq m. The soil gas C values were less than 10,000 Bq m; hence, the research area is categorized as "low radon risk areas" according to Sweden Criteria, and so no special constructions are required in the studied area. When soil gas C values were compared to indoor C values, no linear relationship was found between the C values. However, a strong positive linear correlation was found between indoor and soil gas C values less than 200 Bq m and 2500 Bq m, respectively.