Field tests and analyses for air change rate needed for GMP Grade B area—the background area for manufacturing sterile medicinal products

Tests three facilities in-situ used for sterile medicine manufacture.Through changing air change rates and system operating status, tests and analyses the relationship between air change rate, air cleanliness and clean-down capability. Compares the test results with the theoretical analysis, which show good agreement. The air change rate of 40 h^-1 would be sufficient for the requirement of the clean-down capability for Grade B area, if the contribution from Grade A area is not taken into consideration. The minimum air change rate can be reduced to be about 30 h^-1 , when the clean-down capability from class 7 to class 5 is within 20 minutes. When the ratio of Grade A area to the room area is larger, the requirement of both the air cleanliness and the clean-down capability could be met by the contribution of the circulation and cleaning of air from Grade A area only.