Airthings Corentium Home Radon Detector 223 - Portable Radon Gas Monitor, Lightweight & Easy to Use, AAA Battery Powered (USA Version) - Perfect for Home, Office & Basement Safety Testing

I'm really glad to have this device. When we bought our house 15 years earlier, we had done a radon test and found the levels to be low. But within the last few years I'd started using the unfinished basement quite a bit (home gym), and randomly ordered a charcoal radon test off Amazon. It took me a few months before I finally used it, but after getting the results back, I found that our radon levels were above safe limits (~10+ pCi/L).That freaked me out, and I wanted to quick answers, so I bought this Airthings radon detector from Amazon and had it the next day. It confirmed that our levels were higher than they should be. Further, it also revealed our levels were above safe limits even on the floor above the basement. I'm so glad we didn't have to wait for another charcoal test.A few days later, we had a radon system installed that basically sucks the radon out of the ground, underneath the crawlspace and concrete basement floor. This was a year ago and it has been very effective, reducing our radon levels down to a 1-year average of ~1.3 pCi/L.I've found the Airthings device to be quite accurate, nearly matching the 2-week results from an independent test using two Sun Nuclear radon testing devices.I like how quickly I can get results. For instance, I recently found that opening windows on the top level of our house causes radon levels to increase in the basement (to ~3-4 pCi/L), and this happens due to a chimney effect creating negative pressure in the house, causing it to draw more radon out of the ground. I also learned that I could prevent the negative pressure by also opening windows on the lower level of the house. If I didn't have the Airthings device, I would not be able to tell how these kinds of changes affect radon levels.For any kind of test like this, it's important to give it some time (a day or two minimum), as radon levels naturally increase and decrease all the time, so you can only trust longer term averages. And the longer the test, the more accurate the number. The Airthings device doesn't give you minute-by-minute readings for this reason. Instead, it gives you, short term 24-hour, 7-day, and long term averages, which is ideal.I also like how simple this device us, it's foolproof. There's really nothing for you to do other than finding a good place to put it, and reading its screen. There are no buttons (unless you count the tiny reset button on the back, which you may never use).It shows you the 1-day, 7-day and long-term averages by rotating the numbers every few seconds on the screen. The batteries last a really long time. We've been running the device on the original batteries nonstop for over a year, with no sign of slowing down.Lastly, I also like that you can easily test different places in your house, or even different houses (we recently tested my parents house). It would be a pain to do this with charcoal tests.I highly recommend this device, especially if a charcoal test makes you want further testing, and it is well worth the price. I can't think of any downsides and I will never be without one of these devices.