Variation of radon entry rate into two detached houses

The influence of various factors on the concentration of indoor and its variation were investigated statistically in two different types and location of houses. In the single-storey slab-on-grade house (A), the variation of indoor radon closely followed the difference in indoor–outdoor temperature. The measured pressure difference across the wall and wind speed were significant variables (p<0.00), but these factors explained the variation of the radon concentration only slightly. In the two-storey hillside basement house (B), the most significant variable difference in indoor-attic space explained 28% of the variation of the indoor radon. In both houses, the coefficient of determination increased slightly when the average wind speed increased, but in house B the coefficient decreased with high wind speed. In house A, the highest concentration of indoor radon was observed as the wind-induced internal transport of radon. In house B, the highest concentration of indoor radon occurred and the highest coefficient of determination (100R2%=89%) was observed when the wind was blowing towards the slope-side of the esker, causing increased soil gas pressure and air flow in soil. According to this study, the effect of the wind speed on the concentration of indoor radon and on the coefficient of determination was difficult to foresee because the effect of the wind on soil depended strongly on the wind direction and location of the houses.