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Vapour Intrusion into Buildings - A Literature Review
Citation:
Provoost, J., F. Tillman, J. W. WEAVER, L. Reijnders, J. Bronders, I. Van Keer, AND F. Swartjes. Vapour Intrusion into Buildings - A Literature Review. Chapter 2, J.A. Daniels (ed.), Advances in Environmental Research. Nova Science Publishers, Inc, Hauppauge, NY, 5:69-111, (2011).
Impact/Purpose:
see description
Description:
This chapter provides a review of recent research on vapour intrusion of volatile organic compounds (VOCs) into buildings. The chapter builds on a report from Tillman and Weaver (2005) which reviewed the literature on vapour intrusion through 2005. Firstly, the term ‘vapour intrusion’ (VI) is introduced which, in this chapter, refers to the transport of vapours from VOC sources from ground water or soil into buildings. During the last two decades, soil and ground water contamination by VOCs has received special attention because of their potential to migrate to indoor air and cause human health problems. In urbanized settings of industrial countries, humans spend 64%-94% of their time indoors. Therefore, indoor air quality is of great importance for exposure to vapour-phase VOCs. VI is an active area of research as engineers and scientists try to understand and predict human exposure to harmful vapours emanating from the subsurface. The chapter continues with a discussion of fate and transport mechanisms that move VOCs from source areas (soil or ground water) to receptors (buildings). Sources of organic vapours in the subsurface can come from accidental or intentional releases, leaking landfills or leaking underground and above-ground storage tanks. Once VOCs are introduced into the subsurface, a complex series of fate and transport mechanisms act upon them, potentially moving them away from the source area. The transport processes of advection and diffusion, and the fate processes of (de)sorption and biodegradation are discussed in detail. Soil properties play an important role in the fate and transport of VOCs. VOCs can appear in soil as pure product, as a component of a liquid mixture (gasoline), dissolved in pore water, adsorbed to soil particles, or as vapour in soil gas. The distribution of VOCs in soil depends on the VOC concentration in the soil, soil particle distribution (soil type), soil porosity, pore water content, soil gas content, and organic carbon fraction; it is additionally controlled by the physical-chemical properties of the VOC. Hydrocarbons may be transported beneath residences as a separate phase, dissolved in ground water, or as a vapour in soil gas. Once these contaminants are present near or beneath buildings, they can move as a vapour through soil gas and intrude into the residence. Following this discussion is a review of site studies involving vapour intrusion that have been published in scientific literature, focusing on evidence of the problem’s extent. Published approaches for modelling vapour intrusion are then presented, followed by discussion and conclusions.