Indoor Air Quality, Risk and Uncertainty: The “New” Risks of Vapor Intrusion

Gary E. Marchant.

Uncertain risks present unique challenges to the law. Unlike science, which can always defer judgment until more data are generated and uncertainties are reduced, law must often come to final decisions on uncertain risks that are indeterminate and contested. A relatively new area of uncertain health and environmental risks, which often arise in the context of property transactions, is vapor intrusion. Although the potential for vapor intrusion has always been present on contaminated lands, it is only due to recent legal and policy changes that vapor intrusion evaluation has now become a part of almost every investigation of a potentially contaminated site, and many real estate transactions. This article describes this emerging problem, and the challenges and liability risks it presents for environmental transactions and remediation.

Part I briefly describes what vapor intrusion is and how it is addressed as a technical issue. Part II describes the rapidly evolving legal response to vapor intrusion in the context of clean-up of contaminated sites and property transactions. Part III identifies eleven major issues of uncertainty relating to vapor intrusion, which is making this issue such an intractable and controversial legal, scientific and policy problem. Finally, Part IV provides some practical advice for dealing with the vapor intrusion issue.

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