THIS IS IN SOUTHERN CALIFORNIA, SO WE’RE KIND OF ZOOMING IN ON THAT FOR YOU RIGHT THERE. THE MAPS PUT NEARLY 4 MILLION PEOPLE NOW IN HAZARDOUS ZONES. AND YOU CAN SEE THE COLOR CODING HERE.

where it concentrates and then begins the journey up again as radon gas. Much of the low radon map overlays well with traditional flood zones, in part because basements are rare in these areas ...