z wrote:

... as a general rule of thumb, the government tends to get involved
with things at a risk of 1/100,000 per person per year...

The NSC lists lifetime odds of auto death as 228:1 and yearly odds
as 17,625:1, 77.3 times less. The EPA lists lifetime odds of radon
death as 137:1 for non-smokers at 4 pCi/l, so the yearly odds might
be 77.3x137 = 10589:1, about 10X more than your 1/100000 risk and
twice the auto risk, so why aren't we doing more about it?

Nick