ABSTRACT
The purpose of mechanical ventilation systems is to supply appropriate amounts of clean air and to evacuate vitiated air. However, in field audits it was seen that ventilation systems often host contaminant sources and are, in the worst cases, the main source of air pollution in buildings (Fanger, 1988; Bluyssen et al., 1995, 2000b). Components in the mechanical ventilation system may considerably pollute the passing air. The main sources and reasons for pollution in a ventilation system vary considerably depending on the type of construction, use and maintenance of the system. This chapter summarizes the results of these field audits, and proposes methods to detect the sources of contaminants and strategies to avoid these.
