∑ Increasingthe air changerate or the filtrationefficiency reduces the clearance
timeof the particles.Clearance times of 10±30min are typical for most high-
careareas.
5.5 Waysto reducethe risk fromairborne contamination
Methodsto reducethe risk of foodcontaminationfromthe airborne routefall
into five categories: factory designand factory operation,equipment designand
equipmentoperation,and monitoring.Muchhas beenwrittenaboutthe hygienic
design and operationof chilledfoodfactoriesincluding guidelines fromthe UK
Chilled FoodAssociation (1997,2001),and the variouscontributionselsewhere
in this book.Herewe concentrateon the managementof the air and the design
and operationof opencleaning operations.
5.5.1 Managementof the air
There are many requirementsfor the correct management of the air in a high-
carearea.
Fig. 5.3 Numberof organismson settleplateslocatedarounda room(11.2510.25m^2
floor)afterusingfour typesof cleaningoperation.DatafromBurfootand Brown(2004b).
The hatchedareasshowthe positionof the equipmenton the floorof the room.
98 Handbookof hygiene controlin the foodindustry