The World Health Organization has decided that the acceptable level of Radon in a property is now 2.7 pCL/l instead of 4.0 pCL/l. This means that MOST of the US is now a Zone 1. The old Radon map of the US currently shows three zones with Zone 1 indicating possible levels of Radon exceeding the 4.0 range, zone 2 ranges from 2 to 4 pCL/l and Zone 3 are the areas of less than 2.
So the new map, when it is redone, will indicate 2 zones: areas of over 2.7 and all the other areas.
Happy listing and selling real estate.