We often get asked why radon levels fluctuate, often dramatically, during the 48-hour test period and whether there is cause for concern. There are many reasons for this and the fluctuations are perfectly normal, but this emphasizes the reason that a long term average gives the best indication of whether radon is truly elevated in the home.
The most common reasons that radon levels fluctuate can be broken down into three basic categories:
Air pressure differentials in the home;
Use of exhaust devices that vent indoor air to the exterior;