A method of apportioning indoor radon concentration to the constituent building components

Indoor radon concentrations in high-rise buildings are found to be affected by two majorfactors, namely the ventilation rate and the radon production rate of building materials. In thispaper we present a method to apportion the indoor concentrations to their individual emissionsources. The method consists of two parts: one part is to determine the overall radonproduction rate in a sealed room space, and the other part is to determine the radon productionrate from a particular component. The methods are based upon mass balance models. Theradon concentration profile was typically measured over a period of not less than 3 days. Inorder to quantify the whole room radon production rate, the room was sealed during themeasurement. In the apportionment test, a radon chamber was established on site to measurethe emanation rates of the covering materials directly. Covering materials includingwallpaper, wooden floor covering and windowsill counter-top granite were involved in theapportionment chamber test. It was found that the wooden floor covering greatly reducedradon emission from the bare concrete slab, while concrete walls and ceilings with a coveringof wallpaper were the dominant emission sources. The granite windowsill, which had nocovering material, was in between the wallpaper and wooden floor covering. The chamber testis an effective way to identify potential radon contributors in an existing building. Followingthe sealed room or apportionment method, the radon production rate of the building materialcan be obtained.