Country

Radon concentration (Bq/L)

Reference

Range

Mean

SD

Turkey

0.7 - 31.7

–

[40]

Egypt

(12.90 - 31.33) × 10⁻³

20.59 × 10⁻³

2.42 × 10⁻³

[41]

Nigeria

–

14.8

1.4

[42]

USA

8.4 - 403.0

50.8

–

[43]

Ghana

2.15 - 28.70

8.1

2.6

[14]

India

2.37 - 171.35

22.62

[44]

Cameroon

0.11 - 1

0.48

0,2

This work