Originally Posted by
Zero102
Swings like that are normal. This is why the general advice is against continuous reading monitors - they tend to motivate people to do unnecessary mitigation. Honestly you need at minimum a 30, preferably 90 day average to get a real indication.
Look at my readings, one day it's 20, the next it can be 1500+. Radon doesn't seep into the home at a constant rate, it sorta bubbles up through the ground in spurts and the times it comes in and the times it doesn't can be controlled by temperature, humidity, water patterns in the ground, wind, etc. The only pattern we have noticed with our radon is that the radon levels spike when there is a temperature change, then dip for a short while after, and if the temperature stays constant it will then return to ~100-200Bq/m^3, and even then this pattern only holds about 75-80% of the time.
Basically, don't worry if you see a few readings in the 200s or even in the 1000s, it's about cumulative exposure, long-term readings. If you want to feel better about it, just reduce the time you spend inside the house on days where the readings are high until you've got a long enough time frame to see your true average. Do not, however, turn on exhaust fans thinking you are solving the problem, anything that reduces the air pressure in your house may draw additional radon into the house from below.