NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the Councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consis- ting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. THE NATIONAL RESEARCH COUNCIL was established by the National _ Academy of Sciences-in 1916 to associate the broad community of science and technology with the Academy's purpose of furthering knowledge and of advising the federal government, The Council operates in accordance with general policies determined by the Academy under the authority of its Congressional charter of 1963, which establishes the Academy as a private, nonprofit, self-governing membership corporation. The Council has become the principal operating agency of both the National Academy of Seiences and the National Academy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Academy of Engineering and the Institute of Medicine were established in 1964 and 1970, respec- tively, under the charter of the National Academy of Sciences. TEE COMMISSION ON SOCIOTECHNICAL SYSTEMS is one of the major components of the National Research Council and has general responsibility for the cognizance over those program areas concerned with physical, technological, and industrial systems that are or may be deployed in the public or private sector to serve societal needs. THE ADVISORY BOARD ON THE BUILT ENVIRONMENT is that unit of the Commission on Sociotechnical Systems which ‘focuses on those scientific and technological issues that are critical to the improvement of national policies and programs for the built environment. This report was prepared under contract number DNA002-80-C-0011 between the National Academy of Sciences and the Defense Nuclear Agency. For information regarding this document, write the Executive Director, Advisory Board on the Built Environment, National Research Couneil, 2101 Constitution Avenue, N.W., Washington, D.C. 20418. 5008311