Over the past several years, considerable public and private efforts in this country have been directed at reducing the risk of cancer that human exposure to high levels of radon gas poses. These efforts appear to have succeeded in raising public awareness of radon and in increasing testing for radon. For the most part, however, these efforts have been directed toward homeowners and have not addressed the problem of radon in residential rental properties. Yet, in 1989, nearly 34 million homes—over one-third of all housing units in the country—were rental units.

A more substantive precautionary principle of international law is evolving as new treaties articulate new measures of precaution in different contexts. Although there is considerable controversy over how to articulate or define a precautionary "principle" of law, the goal is to ensure that the mere lack of scientific knowledge about risks cannot justify a failure to take appropriate precautions. Where we have sufficient evidence of risk, we often take precautions, despite a lack of certainty about those risks.

Editors' Summary: Although the Clean Air Act is the primary tool used for controlling air toxics, the dramatic increase in toxic tort cases brought under common-law theories such as nuisance, trespass, negligence, and strict liability for ultrahazardous activities has raised concern in the industrial community that compliance with regulatory requirements may not protect industry from large-scale toxic tort liability. This Article analyzes the implications of common-law liability on the selection of air quality controls.

The Resource Conservation and Recovery Act (RCRA), the Clean Water Act (CWA), and the Clean Air Act (CAA) represent federal regulatory regimes for protecting the environment. Although each statute initially places administrative responsibility in the hands of the U.S. Environmental Protection Agency (EPA), each encourages states, to varying degrees, to take primary responsibility for implementing the statutory regime.

In Environmental Federalism Part 1: The History of Overfiling Under RCRA, the CWA, and the CAA Prior to Harmon, Smithfield, and CLEAN, the history of judicial and administrative decisions relating to overfiling under the Resource Conservation and Recovery Act (RCRA), the Clean Water Act (CWA), and the Clean Air Act (CAA) was analyzed. The history showed that the U.S. Environmental Protection Agency (EPA), with limited exceptions, generally was understood to have overfiling authority under RCRA, the CWA, and the CAA. The limited exceptions focused on two situations.