The airflow in the class 1 areas is similar to that of the class 100 area.
The big difference is that, from above, air is admitted very evenly across the whole ceiling. The sets up a "laminar flow" condition where the air flows downward without turbulence through the Fab floor. In this way, if any dust IS released by operators or equipment, it will fall straight down through the floor grates avoiding the wafers.
