My area has no or very little Radon.  Seldom I hare of a test and the last one that was done on one of my listing was a '0'.

All within safe limits so far.

I have never had a radon test in this area.

I have seen in the 6's and 7's. Radon tests are not used very often in my market area.

The highest was right below 9 picoCuries per Liter. We just had the seller pay for a mitigation system, and after installation, the reading was below 1.5. The concentration really goes off the chart when a listing is vacant, and the air does not circulate.

I think maybe above 10 but after mitigation it is always with  in limits.

We don't have this situation in our marketplace...

The worst case I saw was 4 times the recommended minimum level. Obviously it got fixed!

We have radon pockets throughout many of the counties we serve.....I think 17 was the highest.

I thankfully never had any experience with radon. California, I believe, has a small percentage of houses expected to have elevated radon.

I can't recall that. I only had one transaction where it became an issue. It was quickly taken care of. 

14, and the sellers installed a radon mitigation system, retested it and we moved forward.

Hi Margaret, and had a home under contract last summer with a 44.    This neighborhood is notorious for high levels.   Got it mitigated, and was under 4.0 by closing.

Margaret Rome, Baltimore Maryland - this was the biggest surprise for me. For a condo on 2nd level (yes, second level) had 14.x as radon! Goes without saying, the first time home buyers were nervous and backed out.