When are closed building conditions required for radon testing?

Closed building conditions are essential for radon testing to ensure that the measurement reflects the actual radon levels present in the home or structure without interference from external factors. These conditions help to provide a consistent, controlled environment that can produce accurate readings.

A test lasting less than four days requires closed building conditions because shorter testing periods can be more susceptible to fluctuations in radon levels caused by ventilation, external weather conditions, or other disturbances. By maintaining closed building conditions during such tests, you minimize the risk of obtaining misleading results due to these variables.

In contrast, tests longer than a certain period may not necessarily require closed building conditions throughout, as they would naturally average out daily fluctuations in radon levels over time. Long-term tests aim to provide a more comprehensive assessment, accommodating for minor variances, and can rely on a broader range of environmental conditions that might exist during the testing period.