Table 8
Natural Levels of Rn-=-222
Estimated Mean
Range
Area
Reference
Fresh Water
10° - 10? poi/i
Precipitation
3
19 pci/l
3
Ocean Water
"Close to equilibrium with Ra-226"
A
Air - Indoors
DUC wim
2
Outdoors
Over Qceans
Internal Dose - Lung
209 poi/m?
30 = 500
2
0.5 = 19
3
"Several hundred mrad/y"
Ww
Lakes and Hivers