I got the results back from my radon test and the good news is there is no giant radon field in my kitchen.
I tested the granite with 2 radon kits with 2 canisters each.
I placed 2 on the counter near the sink, where I spend inordinate amounts of time. I taped a square around them to help keep them in the same place over 4 days.
I put one on the center island.
And I put one on the kitchen table, which is NEAR the granite, but is NOT granite.
I resealed the little bottles and sent them off in their prepaid envelopes. Days later, I received an email report and then a report in the mail.
The one on the kitchen island measured 0.3 pCi/l (picocuries of radon per liter of air).
You start worrying at 4 picocuries and none of my canisters measured anything near that. The one nearest the sink and probably the place where I spend the most time is 0.6, still REALLY low. Interestingly, the canister close to that one was only 0.1. I'm not sure why there was any difference 12 inches apart. The one on the kitchen table, which isn't even stone, was 0.1.
Wait a second, the canister, which was sitting on a ceramic tile table (NOT stone), measured the same as the one ON granite, so I guess I REALLY have nothing to worry about.
I called my radon expert and I spoke to Mrs. Radon Expert. She said it might have been interesting to test the basement at the same time (which we did years ago when we bought the house). She said, in general, whatever you have on your first floor is half of what's in your basement, because radon always goes to the lowest part of a house. But there were no levels on the first floor that were anything to worry about, so even if I doubled them to compute the basement levels, we're okay.
What did I learn, besides the fact that I'm easily spooked? I learned that MY granite is safe, but I have no idea about YOUR granite or any other granite for that matter.
If I ever bought more granite, I might try to find a purveyor that tests its slabs for radon BEFORE they were installed and I would get a presealed granite. Home Depot, for one, now sells only "PermaShield" granite, which is presealed and requires no home maintenance EVER and presumably cuts down on any radon escaping into the air.
Note: They don't call it a sealer. They say "PermaShield® protects natural stone through a proprietary process that is unlike anything else on the market. PermaShield® is not a sealer." Whatever...I get the idea.
I don't have this fancy space-age granite, so I will certainly get my granite resealed, which may...or may not cut down on the radon risk even more, but, at least, it will look all nice and shiny.