What could explain a higher radon measurement on the first floor compared to the basement?

Higher radon measurements on the first floor compared to the basement may be attributed to several factors, but the most compelling explanation is related to indoor activities that may promote radon release. When considering higher water usage on the first floor, it suggests that activities such as showering, washing dishes, or using washing machines can increase radon levels due to aeration processes. Water can carry radon gas from the soil into the air when it is disturbed, which may lead to higher measurements in living areas where there is increased water use.

Additionally, the interaction between water and radon is significant. If there is a higher level of water activities on the first floor, it can mobilize radon dissolved in the water, releasing it into the indoor air. This would explain why radon levels might be higher upstairs rather than in the typically more enclosed and lower ventilation areas of a basement where radon usually accumulates.

Understanding the nuances of air movement, ventilation, and indoor activities is crucial in radon measurement evaluations. This helps clarify how environmental factors impact radon exposure measurements in different areas of a home.