The conditions for people who work in underground facilities has, to a very limited extent, been the subject of serious discussion, problem analysis or research. Knowledge within this subject area is, as a result, very limited (Chapter 2). A framework of reference which demonstrates the factors which influence human beings' reactions to spending periods of time underground and how these factors interact needs to be developed (Chapter 3). A more extensive expansion of underground space where human beings will spend periods of time ought not to be explorated before more is known about the effects that can occur and the causes of these effects. If after thorough consideration it is decided to site an activity underground, the underground space must be dimensioned and designed in such a way that disadvantages, for example lack of windows and reduced accessibility can be compensated for to the greatest extent possible (Chapter 4). Continued R and D work on these problems must be carried out (Chapter 5).