Climate change, disaster, here is one more thing to worry about. Something I did a year ago, start to measure radon in my house, made for quite an experiance last winter.
I tested radon in my house when I moved in after checking and validating my detector in the old house. It was about 3 in late summer. A couple years later I decided to plug in the detector in April. It was high about 9. I was concerned because it was almost that upstairs. It tricked down to 2.5 in summer. In late October it rose to 20. I installed a temporary suction pipe to the backyard. Went quickly down to below 4. Rose and reached a peak in December about 6-7. My radon levels may have been over 35 without suction. I had no idea. You must check levels in all seasons and weather conditions else a single measurement tells NOTHING of yearly levels. I didn't see any difference in my electric bill, but I turned it off for now, around 4 or so. In my case it was mostly suction, for there was little CFM comming out of the pipe. I will be installing a pipe up through the roof. before winter. I would suggest getting a monitor as I did. The levels were pretty consistant with a slow level change. I also tried to blow out the house at times, and that did very little for any daily change. A level 4 is median point. Probably like smoking 1/4 pack of cigarettes a day. 16 equaling 1 pack. Your getting at least 1 cigarette a day by being outside sucking in radon. These levels are guesses but what can you do.
I started using one of those fiber electrostatic filters last winter as I always do, but experimented. I also tried the best one from 3M. The filters can actually become harmfull after filtering. It will reach a peak in about 4 days. I measured levels on the filter using a counter of 10 times the background levels. They don't appreciably reduce the ambient radon level, even when using an added charcoal filter. They do collect however. You can't measure radon with a counter witout using the air/filter method. My radon counter does use a Muller tube, but uses a very slow integration time to detect it, and only reads after 2 days, but keeps averages for over a year.
I also noticed that level changes can occur depending on open windows and air flow. An open window downside will suck more radon into your house.
I live near Pittsburgh Pa. USA
greg