A Probabilistic Approach for Evaluation of Radon Concentration in the Indoor Environment

Abstract

An analytical method based on structural reliability has been developed with the objective to ensure a healthy indoor environment for people in residential buildings. The method has been applied to a model of the foundation of a house, which is principally a concrete slab on the ground, when the hazard to the indoor environment is radon. The reasons why radon is found indoors have been identified using fault tree analysis. Random variables in the model are defined such that resistance is the ability of people to withstand the radon concentration indoors without adverse health effects and the load effect is equal to the top event of the fault tree and is a function of the environmental load and the decisions made in the building process. A quantitative evaluation was made using both Monte Carlo simulation and First-order second-moment theory where the load effect is compared with the resistance defined as the threshold value for radon concentration indoors stated in the Swedish Building Regulations. The objective was to calculate the probability for exceeding the threshold value and to estimate analytically the safety index. Other interesting areas of application of the developed model could be for the environmental impact from moisture causing growth of micro-organisms and release of chemical emissions, or from soil contaminates like, for example, petroleum products.

Keywords

Indoor environment Fault tree Radon Probability theory Structural reliability

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