How many hours should closed-building conditions be maintained prior to tests lasting less than four days?

Maintaining closed-building conditions for a specific duration is crucial for accurate radon testing. The correct duration of 12 hours ensures that the indoor environment stabilizes, allowing radon levels to be accurately measured without the interference of external factors such as open windows or doors that could dilute radon concentration.

This 12-hour period allows for the accumulation of radon gas, reaching a stable level that reflects realistic indoor conditions. It is particularly important for tests lasting less than four days, as a shorter pre-test period might not provide sufficient time for radon concentrations to reach equilibrium.

By adhering to this timeframe, test results are more likely to be consistent and reliable, thereby enhancing the effectiveness of radon monitoring programs.