I've had a home office in the basement for years, but due to Covid found myself spending more time down there than ever. A month or two into lockdown I seemed to be having shortness of breath issues and thought for a while that my mind was just playing tricks on me, "do I have the sickness..."? Well, I let that go for a while and when it didn't get better I did some research and decided to check my radon levels. I started with a mail in 3 day charcoal kit which came back somewhere in the low 4 range, not great, not terrible either since 4 is the recommended max level. Finding out that radon can vary over time, I decided to buy the Airthings Radon sensor. Overall, setup was quick, I agree the bluetooth design is a little annoying, but I've never had an issue syncing as long as I was in the normal 30foot range that bluetooth has. It doesn't sync in the background, only when you open the app. A WiFi option would be nice, but that would require a power cord, and I did appreciate that I could move this device around to several locations in the house which was easy with it being on batteries. Accuracy: After the 48 hour "acclimation" period, I saw the reported radon levels come right into line with the lab report. Then it kept climbing, then it dropped to almost nothing back in the green range, then back to red. Over and over every 2-3 days I'd be green, red, green, red, and I started to wonder if it was just a gimmick to make it look like it was doing something. It did seem to change with weather, but I could never put my finger on a pattern as the weather is always changing. Then I moved it from the basement to the main level for a few months, and the average was slightly lower, but I still bounced between acceptable and unacceptable levels. Finally, somewhere in the process I got actual Covid, got over it, and felt pretty much the same as before but I started to notice I felt better when I wasn't at home. We traveled for Christmas and had a vacation or two since someone has to keep the economy going... So I finally decided to install a radon fan on the passive pipe which was installed on our house during construction as required by code these days. The Airthings device had no way of knowing I just installed a fan, but it clearly picked up on the environmental change. In the screenshot you can see the radon level fall off a cliff and flatline in the green. In short, I no longer question if it was actually measuring anything, this thing works! I was surprised by the variability in radon levels over time, and I'd recommend anyone who's concerned to get a sensor like this. Go ahead and get a lab test as well just to confirm the sensor is good any working, but I do think there's a delay between your radon level and when it shows up on the sensor. This is surely why they tell you to wait 48 hours after setup before looking at the reading. I tried many times to open a window in my office when it turned red and never saw a blast of fresh air to make a difference. I'm not a physistist, but the sensor probably takes time to absorb or react to the radon, so let it sit and watch the trending over time. It's only been a week since installing the fan, and maybe my brain is giving my lungs a placebo effect, but I feel like it's made a difference.