An early example of the problems of air borne contamination in buildings and the dangers, is the legend of "The Pharaoh's Curse".Those who opened and entered the Pharaoh's tomb disturbed the dust which contained fungi spores that had lain dormant in the dry atmosphere for centuries. The fungal spores burst into life when they came into contact with the first moisture available. Unfortunately, the moisture was inside the lungs of those who first entered the tomb, resulting in a serious loss of "productivity"! Today we are more than ever aware of both natural and man made pollutants that contribute to a range of problems and illnesses that threaten and impact on the occupants health and "productivity". There is a requirement to protect visitors, clients, staff, customers and processes carried out in areas served by ventilation systems. Contamination often builds up in the neglected or frequently forgotten air distribution systems.