What factor must be considered when interpreting results from long-term detectors in radon measurement?

When interpreting results from long-term radon detectors, seasonal changes in radon concentration are a critical factor to consider. Radon levels can fluctuate due to variations in temperature, humidity, and atmospheric pressure throughout the different seasons. These fluctuations can affect how radon enters a building and how it accumulates within the indoor environment. For instance, radon levels may be higher in winter when homes are sealed against the cold, leading to poor ventilation, compared to warmer months when windows are open and air is circulating more freely.

A long-term measurement device is designed to capture average radon concentrations over an extended period, typically more than 90 days, which helps provide a more accurate account of a building's radon levels throughout different seasons. Understanding these variations is essential for accurately assessing the potential health risks posed by radon and for making informed decisions about mitigation strategies.