In summarizing results of measuring air-borne particulate concentration in over 15 clean or ultraclean facilities, it is evident that three major sources of particles are present: (1) those associated with the air supply, (2) those associated with the processes conducted within the room, and (3) those associated with the personnel in the room.

Each of these potential sources has specific problems which must be considered. The air supply in the cleaner facilities utilizes high efficiency impingement filters to provide low levels of concentrations (0.1 particles per cu cm) for the microscopic size particles. Those processes involving high temperatures, combustion, the utilization of gases, paper products, or abrasion must be carefully controlled. The presence of people in a clean or ultraclean room is very critical and the number and activity of the personnel can be correlated to the level of contamination in a room and, therefore, must be carefully controlled.

A more detailed analysis of these three sources of contamination is presented, including tables of typical values of air-borne particle contamination for classes of clean facilities, common processes conducted, and personnel present.