Particles, particles everywhere! What is a lab to do? Sources of these contaminating specks are many: equipment, room materials, unfiltered air, bacteria and mold, clothing, and (the biggest culprit of all) people. Facilities make heroic efforts to keep the adulterants at bay, but some amount of contaminants will find their way into the controlled space.
Until processes become fully automated, personnel will still need to step into cleanrooms to perform application-specific tasks and service equipment. Best practices guide these workers, but it’s impossible to contain every particle that’s just begging to float around the room or land on surfaces.