Possibly, but not necessarily - there are many variables to consider. Radon levels fluctuate every hour of the day and from one home to the next due to many factors such as the amount of uranium, radium, thorium, and other radioactive elements in the soil and how quickly they are breaking down around the structure. The insulation of the home also has a lot to do with how concentrated the radon is, because a building that breathes will vent some of the radon, whereas a building that is well-insulated traps air (and thusly radon) inside.
The only way to know a structure or home's radon level is to test.