I would not be concerned with the reading you're getting. In my area radon is pretty common and I wouldn't expect to find a house that met all of my criteria but did not have radon.

It's not uncommon to be concerned. Although the readings you are receiving are well within limits, if you want additional peace of mind, there are plenty of radon specialists out there. I'mnot sure what area you are in, but if you simply google something like "radon mitigation near me" you should be directed to at least a few. They are typically more than happy to interpret your reading, explain your mitigation and how often you should retest, and answer all your questions. My own house has air and water mitigation for radon and we use the basement as well. Good luck!

Radon levels fluctuate. So the 1.5 reading you got was the level reading right that minute (which is still very good by the way).

We have had a radon mitigation system in our basement since 2004. We bought a meter that not only measures the reading at that minute, but also did a 30 day average.

We recently finished our basement and had the mitigation company come out again and performed their old readings since the meter we bought was several years old. Turns out their readings were the same as what our meter showed.

But in order to have more peace of mind, we had a new meter installed that has an app where we can look at an hour by hour reading if we so choose. It also does monthly averages. I will say since our basement has been finished, out readings are consistently right around 1, where before finishing they were around 1.5 to 2. The level before our mitigation system was installed was I believe 6.

Edit to add that it also depends on what part of the country you live in. Colorado, for instance, has very high radon levels and you will likely never test below 1 no matter how good your system is.

Radon is everywhere, even outside. It becomes a problem when it is trapped and it accumulates. That is the reason for higher levels. Radon mitigation is simply a venting system. You can always open a window in the basement if that makes you feel better.

Here's the EPA website on radon

https://www.epa.gov/radon

Here's a map showing radon across the US

https://geopub.epa.gov/Radon/

Since radon is in the ground, it seems possible other homes in that town have it too. You've probably already decided on whether to buy that house or not...but it makes me wonder if your realtor can share any info; i.e. if radon is more of an issues in some parts of town vs. others. Good luck!