Grade A

The cleanest zone for aseptic operations, such as the filling point, open sterile containers and aseptic connections, typically provided by unidirectional airflow, an isolator or a restricted access barrier system. Particles are monitored continuously during operations, and the microbial expectation is no growth. Under EU GMP Annex 1, a Grade A zone in a conventional cleanroom sits in a Grade B background, while an isolator may sit in a lower grade. Japanese documents use the same letter grades.