Review on Portable Home Radon Detector - Elifecity Long and Short-Term Radon Meter, Battery-Powered & Easy-to-Use by Jason Ingram

I'm not a scientist, but I just decided to conduct an experiment on accuracy. Since the device must have access to air (to be able to measure gas in air*) I figured if there was no access to air it shouldn't show readings like 0.00. I did a reset, removed the batteries and left it in my yard for about 20 minutes. I then put the batteries back in place and immediately put them in a ziplock bag to make sure the air was expelled, then placed them in an airtight container. It showed 3.57 long and short term after 24 hours. At least the two values were the same. However, I bought another device that was placed under the same conditions and read 0.02 in the short term and 0.37 in the long term, which I think will get closer to 0 if I keep it longer. * If the device does not require air (e.g. if it detects gamma radiation), there is no point in isolating it in a sealed container. But it says that the device uses the method of alpha spectrometry, so it's up to you to decide the accuracy.