Highest Radon Reading?

For the folks that provide radon testing, what’s the highest reading you’ve gotten? I’ve tested for almost 3 years, and the highest was a house with a 22 pCi/l. Then this week, I got into a house that measured 108 over a 78 hour test, then I re tested and it came out with 119 over 48 hours. I ran an equipment test in between at my house to be sure there was not an equipment problem. Anyone else?

what kind of radon test equipment are you using?

Hi David,
I use Radalink telemonitors.

Check measured RADON levels in your county here:



The highest I have tested for in 4 years is 18 Pci.

I hope the people that live in the house didnt smoke or there risk is of the charts!!!

I worry about my basement that is 3.4.


At a HI chapter meeting, a Radon expert informed that a home just one mile from where I lived had levels approaching two hundred. An old couple had lived in the home most of their lives and the wife has been sick with one thing of another most of her life.
Readings levels are seasonal and are highest when the greatest differences in atmospheric pressure are in play, i.e., windy days.
That’s all I know.

Anyone else want to share the highest levels they’ve gotten? It’s just curiosity, I’m not writing a book or nuthin’

32 pCi/l. In Connecticut.

147 in Connecticut.

10 in Ontario Canada

Paul Hinsperger
Hinsperger Inspection Services
Orangeville Ontario

Varies around town in KC but there are definite pockets - like by Cedar Creek, or by the ballpark, or by Parkville, Weston.

Found some in upper 70’s and low 80’s by Parkville or Weston.

In Columbia I would expect pockets out by the quarry or near Peters place.

I think my highest was a little over 20,000 pCi/l (north central Colorado).

Caoimhín P. Connell
Forensic Industrial Hygienist

Hi to all,

I thought I had everyone beat until I saw [FONT=Verdana][size=2]Caoimhín’s

My highest ever was just under 1400 PCi/L in Atkinson NH



Caoimhin, was that in a home?, I have never seen an above ground reading anything like that.



Mine was 225 just south of NACHI worldheadquarters in Colorado. I have heard of higher readings but they generally involved waterborne radon.


Probably one of Nicks mining hideouts. Even Stanley Wattrus didn’t have readings that high


I had one in the foothills in western VA that was 55. When I was in class (a gazillion years ago) I was told that readings in PA had come back at over 2000. Must be Uranium in them thar hills. :smiley:

Hello Gerry –

The 20,000 pCi/l reading was from a sub-slab core. We drilled a hole through the floor of a poured foundation wall basement, and sampled the air surrounding the slab. The reading is an actual disintegration rate, and not (like all radon readings) a “radon concentration.” As I’ve discussed here in the past, none of the disintegration readings expressed in pCi/l are actually “radon” concentrations.

They are just a standardized U.S. EPA expression of PAEC, the readings are NOT radon levels.

Caoimhín P. Connell
Forensic Industrial Hygienist

How far south, Rick?

Caoimhín…now really. 20,000… that’s not a typo?