Soil Permeability
Soil permeability or texture is considered a predictive factor for high radon concentrations. Soils that are sandy or gravely, are more permeable than finer soils.
Dry or cracked soils have been linked to higher radon variability because it increases soil porosity and the influence of atmospheric conditions. Another aspect of soil permeability is when basement and foundation types come into direct contact with aforementioned soil types, affecting the likelihood of high radon concentrations.
Foundation Type
A different foundation type (basement, crawl space, and concrete slab) has a meaningful impact on variations of high residential radon concentrations.
As Lower levels of structures are often poorly ventilated, homes with a basement or semi basement foundation are likely to have greatly increased levels of radon when compared to levels found in homes with only slab foundations
Seasonality and Heating Systems
Variability in radon measurements can also be linked to seasonal changes and meteorological factors. Highly permeable soils have higher radon gas concentrations in the winter than in summer due to winter freezing which effectively locks radon in the soil; the atmospheric conditions of the summer work to release stored radon in loose soils.
As well as this elevated concentrations have been found to be higher during winter months due to a combination of a lack of air circulation and shut windows and doors.
Year of Construction
Older homes are going to have higher concentrations of radon because they typically have more cracks in flooring and the foundation and thus have higher risk of contamination Indeed, older structures provide many pathways for gasses to seep in, but new buildings can be found to have high concentrations regardless of geology.
In addition, features synonymous with older housing such as smaller rooms and poor ventilation have been found to be a precursor to high radon levels.
