Opinion ID: 1176318
Heading Depth: 2
Heading Rank: 3

Heading: Radon-222 Concentration at Vent Height

Text: No measurements were made of the radon-222 concentration in outdoor air at a height of 0.36 meters, the height at which air entered the crawl space of the hypothetical house. All parties agreed that radon-222 concentration decreases with height, but the parties could not agree upon the precise relationship between height and concentration. EFSC, on the basis of published studies of radon-222 concentration variations at heights below one meter, determined that the annual average radon-222 concentration at 0.36 meters was 8.05 picocuries per liter for SL and 2.34 picocuries per liter for LRP. TWCA, using a theoretical model of air movement, argued for lower values  6.0 and 1.6, respectively. Petitioners, extrapolating measured variations in radon-222 concentrations at heights above one meter to heights below one meter, argued for higher values  10.1 and 3.03, respectively. There was evidence, however, that variations in radon-222 concentration at heights above one meter could not be extrapolated to calculate variations at lower heights. EFSC's findings in this respect were not unreasonable.