Introduction. Off-gassing properties of materials are normally regarded as a problem only in confined spaces designed for long-term stay, e.g. nuclear submarines or manned spacecraft. The problem, however, is of general hygienic importance as a multitude of airborne contaminants are being generated within the home environment from building materials, fixtures, furniture, textiles and various household products. The purpose of this article is to analyze the emanation of formaldehyde from chipboard used as a building material. The dependence of the emanation on indoor climatic parameters is described and a mathematical model is developed for prediction purposes.