What type of tests require more time but are more likely to reflect a year round average?

Long-term tests are designed to monitor radon levels over an extended period, typically ranging from 90 days to a year. This duration allows for the capture of variations in radon concentrations due to seasonal changes, ventilation practices, and occupancy patterns. Because radon levels can fluctuate significantly due to factors like weather and time of year, long-term testing is more effective for obtaining an average that accurately represents the annual exposure households are likely to experience.

In contrast, short-term tests usually last for a few days and can provide quick results, but they can be significantly influenced by temporary conditions and may not represent the year-round average accurately. Instant tests, although quick to conduct, simply provide immediate results without considering the variability over time, while random tests lack a structured approach to gather data consistent enough to produce reliable averages. Therefore, long-term tests are essential for accurately assessing radon levels over a more representative timeframe.