I ask because when I purchased my home the level was 19 pCi/L, and on a recent retest it is 27.8 pCi/L. I plan on for sure getting this fixed within a month, but I'm wondering if there's any reason to make it priority to get it done sooner. Most of the statistics, etc. on the danger talk about the effects over a lifetime, how much radon would it take for there to be an immediate danger to be living in the house?
According to this Radon Dose Calculator, if you are exposed to 30 pCi/L the dose rate is 6.275 µSv/h. Multiply by 30 days and 24 hrs/day to get 4500 µSv, or 4.5 mSv dose over 30 days.
Wikipedia suggests that is similar a CT scan (which is a significant dose). You are probably not in the house 24 hours a day so you could adjust the numbers downward.
Here's another nice visualization of different doses.