Why must short term radon tests be conducted for at least 48 hours?

Conducting short-term radon tests for at least 48 hours is important because it allows the test to capture at least two daily cycles of radon levels. Radon concentration can fluctuate based on various factors, including changes in weather conditions, temperature, and pressure, which can affect how radon gas moves and accumulates in a home. By extending the testing period to 48 hours, the test accounts for these fluctuations, leading to a more accurate representation of the average radon level in the environment during the testing period. This helps in evaluating whether action is needed to mitigate radon levels effectively. Therefore, the length of the test is crucial for understanding the true radon exposure and ensuring that the results are reliable.