Radon control systems in existing and new construction: a review

Abstract

In support of the implementation of the new Canadian radon guideline, a comprehensive review of radon mitigation techniques used in countries around the world was undertaken, with particular emphasis on North America and Europe that have climates and construction techniques similar to Canada. The results of this review are presented here as an aid to administrators of radon control programmes, companies offering radon testing and mitigation services and other concerned parties, both in Canada and elsewhere, who are facing issues of implementing a radon control strategy. A wide variety of radon mitigation strategies have been employed worldwide and all have achieved some success in reducing radon concentrations. Generally, active mitigation techniques involving physical alterations to a house (e.g. sub-slab depressurisation) are more effective in achieving a sustained and substantial radon reduction than passive techniques (e.g. improved ventilation or sealing of cracks). To a large extent, the choice of an optimal mitigation strategy will depend on the building type, soil conditions and climate. Radon levels should be measured at periodic intervals after remediation, perhaps once every 5 y, to ensure that concentrations continue to remain at acceptable levels.

Development of a model for radon concentration in indoor air

“…The soil or the building ground under the building site is the most important source of indoor radon in Norwegian dwellings, while building materials and household water from drilled wells are rarely the main cause of indoor radon concentrations exceeding the action level of 200 Bq/m 3 given by the Norwegian authorities (TEK 10 -Byggteknisk forskrift 2010, Rahman and Tracy 2009). It should be noted that there is an on-going discussion in Norway if the action level should be reduced further for new dwellings.…”

“…Refer to e.g. the review by Rahman and Tracy (2009) for radon control systems in various countries. It should also be noted that radon levels that are regarded as low levels today might not be considered as low levels tomorrow.…”

Physical Factors Affecting the Interior Radon-Concentrations

“…In different countries, Rahman and Tercy have reviewed the radon-222 control systems [9]. It should be noted that the "low-levels" of radon-222 in some days might not have the low values the day after.…”

“…Different analysis to pre-estimate (and to model) the inside-radon-222 concentration is found in the scientific literature. For example, several authors have studied the different variations of radon-222 concentrations (seasonal variations) with prediction through model calculations [10][11][12][13]. Also, pre-estimation due to premier calculations, after these models, demonstrate that there is some contribution from the building materials.…”

Limited applicability of cost–effectiveness and cost–benefit analyses for the optimization of radon remedial measures

“…The only way to decrease the radon dose in dwellings is to decrease the indoor radon concentration. Several types of radon remedial measures are available for such purposes [1]. However, people who have to make decisions on the type and the degree of remedial works have no effective tool for selecting the best solution.…”