What is the minimum length of time for a long-term radon test?

The minimum length of time for a long-term radon test is 91 days. This duration is established based on research and standards set by radon measurement professionals and organizations. Long-term testing carries significant advantages, as it allows for a more accurate assessment of radon levels, accounting for fluctuations in radon concentration that may occur due to seasonal changes, weather patterns, and ventilation variations in the building.

By measuring radon levels over at least 91 days, the test provides a more comprehensive average concentration, which is essential for accurately determining potential health risks associated with prolonged radon exposure. This is particularly important because short-term testing may not fully capture sporadic high levels that could occur, leading to an underestimation of radon exposure and associated health risks. Thus, the 91-day timeframe has been recommended as the minimum duration to ensure reliable data for making informed decisions regarding radon mitigation and safety.