Correction: Seasonal 222 Rn activity in spring water close to rare earth element and uranium mines in North Vietnam

222Rn is among the most important issues for radiation exposure in/near high background radiation areas such as near rare-earth-element (REE) and uranium mines in North Vietnam. Seasonal 222Rn activity concentration in spring water was determined by RAD-7, with average ranges of 1270 ± 60–66,400 ± 2630 Bq m−3, therein the highest value was a REE, and the lowest a uranium mine. The 222Rn activity concentration was higher in the dry season, which could be attributed to 222Rn leaching to spring waters from nearby mines, and lower in the rainy season due to dilution by rain water. The 222Rn annual effective doses were within permissible limits.