Detailed measurements of indoor radon levels in five residential premises and the effect of ventilation.

Detailed radon measurements and ventilation testing were carried out in five residential premises in Hong Kong. Continuous radon detectors were located in the bedrooms of each site and corresponding C02 decay tests were conducted to estimate the ventilation rate. Four air-conditioning operation modes were used in the measurements. Data obtained from the measurements were used to verify the validity of a simple mass balance model.

Radon mitigation in a difficult to mitigate school.

This paper describes radon diagnostics and mitigation in a school the U.S. Environmental Protection Agency (EPA) classified "difficult to mitigate." The school had subslab utility tunnels that served as the outside air and return air mixing chamber for the heating and ventilation system. The heating and ventilation system depressurized the tunnel, sucked radon from the soil, and distributed it to school rooms. Extensive diagnostics were conducted to test mitigation options and to provide mitigation design parameters.

An energy efficient approach for radon management. Part I: Radon assessment.

This paper involves assessing radon concentrations at the heating, ventilating and air conditioning (HV AC) environment of Hong Kong University of Science of Technology (HKUST). Ninety rooms with various configurations were selected at random and evaluated in detail. A time-integrated active sampling instrument as well as a passive activated charcoal canister radon detection system were used for the study. With the central HV AC system in the normal operating mode, data on location characteristics, as well as average and peak radon concentrations were collected and analysed.

An energy efficient approach for radon management. Part III: Radon management.

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.

An energy efficient approach for radon management. Part II: Radon modeling and evaluation.

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.

Radon and natural ventilation in newer Danish single family houses.

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.

Decrease of radon exposure by continuously adjusted and controlled ventilation.

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 %.

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