I guess i mean, is background radiation some form of constant? Is it location dependent? (Duh.) Does it change over time, with the addition of our stuff? And since when did we know what backgound radiation was?

One example of why i want to know: When building codes for passive solar were considered, radon gas was one driver.

Is this discussion even an issue?

"Life shrinks or expands in proportion to one's courage." - Anaïs Nin