The activity of radon daughters in high-rise buildings.
Abstract Forty measurements are reported in similar rooms in two high-rise buildings. The geometrical means for the concentration of radon daughters including and excluding the basement results, respectively, were 0.90 and 1.00 mWL, which is less than the quoted mean 2.0 mWL for 65 measurements in typical houses in the same city. The frequency distribution of these measurements shows a log-normal distribution. The concentrations did not depend on the distance from ground level but may depend on the ventilation rate of the room examined. The correlation between the concentration of radon daughters in WL in rooms above the first floor in the two high-rise buildings with the inverse of their ventilation rate were 0.73 and 0.67, respectively.
Radon levels in a high-rise apartment.
AS PART of the United States Department of Energy Radon Research Program, continuous Rn monitors were constructed based on the design of Chittaporn et al. (1981), and measurements were conducted for 3.5 y in a high-rise apartment. The apartment is located in a small city in Hudson County, New Jersey, across the Hudson River from midtown Manhattan. One continuous Rn monitor was placed outdoors on the 24th-floor terrace and one indoors. Hourly data were measured over the 3.5-y interval and averaged to give seasonal values. The instruments measure 222Rn without interference from its decay products. A 1.7-L scintillation cell, open at both ends, rests above a 12.5-cm phototube. A negatively charged electret over the counting volume collects the positively charged decay products at formation within the cell and removes them from the detection volume. The calibration factor for these instruments is about four counts per hour per Bq m-3, and the background is eight counts per hour. The Poisson counting error (1 s) for a 1-h count at 10 Bq m-3 is +15%. The propagated error for the annual average 222Rn concentration (summation of hourly data over a 1-y interval) is 0.2%. Five of the 222Rn counters have been in continuous use at various research homes in Pennsylvania and New Jersey for 7 y. Weekly grab samples of 222Rn are taken as a check on quality control and counted in flasks that are used for the '"Rn intercomparison in the Department of Energy, Environmental Measurements Laboratory. Our results in all of the intercomparison exercises have been within +5% of the "true" value.
A study of radon emitted from building materials using plastic α-track detectors
Films made from cellulose nitrate LR-115 (Pathe Kodak) and CR-39 have been used for long-term measurements of the radon-222 emanation from building materials and the resultant activity inside houses. The emanation from crushed granite bricks is found to be produced from within the brick while in the clay bricks it originates in the surface layers only. The airborne radon activity inside houses constructed from clay brick is found on average to be 22 mBq 1-1 (0.57 pCi 1-1) while inside a closed vessel sealed to the brick the average equilibrium activity is 40 mBq 1-1 pCi 1-1).