radon

This paper describes the management of radon concentrations at the Hong Kong University of Science and Technology (HKUST). Applying our derived specific modification factor in the radon concentration predictive mathematical models, we were able to accurately estimate radon concentrations under different conditions of Heating, Ventilating and Air conditioning (HV AC) operations. Various combinations of HV AC operating schemes were tested mathematically. Many possible combinations demonstrate optimal effects.

This paper reports on the experimental results using a standard room chamber to evaluate the impact of various parameters on indoor radon concentrations. The paper assesses the suitability of using pro-existing mathematical models for the prediction of indoor Volatile Organic Compounds (VOC) to estimate radon concentrations in the heating, ventilating and air conditioning (HV AC) environment. A test chamber study was conducted to thoroughly evaluate and validate parameters considered in these models.

To investigate the effect of ventilation on indoor radon (222Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984-1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12-620 Bq m-3 and 0.16--0.96 h-1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed.

A new mechanical ventilation system which continuously controlled the indoor-outdoor pressure difference was installed in six houses, where the long-term radon levels ranged from 670 to 3 080 Bq/m³. When the new system had operated for several months, the indoor radon levels decreased to levels from 120 to 600 Bq/m³ , the effective dose reductions being from 40 % to 88 %.

During the past 10 years the U.S. Environmental Protection Agency (EPA) has pursued a national strategy to address radon remediation in buildings to meet its goals of radon risk reduction. Initially the approach developed and demonstrated remediation methods and techniques in existing residences with specific attention to the effect of regional climate variations and the differences in housing construction. A number of studies and demonstrations were undertaken to accurately characterize and evaluate the effectiveness of several remediation methods and techniques.

A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system.

The effects of cracks and holes on the exhalation of radon from concrete have been investigated. It was found that the total radon exhaled from concrete blocks was the same irrespective of the diameters of holes drilled into them, and irrespective of the number of holes drilled. Furthermore, the surface area of the concrete blocks did not have any effect on the total radon exhaled