∑ Ensurethat adequate air is blownin to the roomto maintain a positive
pressure.
∑ Ensurethat air extraction is not so great that it reducesthe pressurein the
high-care areabelowthat in neighbouringrooms.
∑ Allowfor air leakagefromthe high-care areaat the designstage. Consider
whatwillbe the effectof opening doorways,etc.,oncethe factory is in
operation.
∑ Provideadditionalair if furtherair extractsor hoods are subsequently added
to a productionarea following the introduction of newequipment, for
example.
∑ Try not to position air extracts in high-care areas closeto hatchesor
doorwaysconnecting to low-care areas.
∑ Keepthe returnside of ceiling mounted chillersawayfromthe hatchesand
doorwaysleadingto low-care areas.
∑ Designfor the air-handlingand deliverysystem to be accessibleand easily
cleanedand maintained.The systemshouldnot be a sourceof contamination.
∑ Thinkaboutfuture changesto the factory, suchas expansion.
5.5.2 Designand operationof opencleaningoperations
Earlier datahave shown thatcleaning operations can be majorsourcesof
airborne contamination. Gooddesignand operatingprocedures, suchas the
following examples,can helpto minimise theirimpact:
∑ Poorlycleanedequipmentcan becomea significant source of contamination.
Cleaningequipmentshould be cleanedand sanitisedaccording to a defined
schedule. An areafor cleaningshould be providedoutside the production
area.
∑ Hosingcreateshighconcentrationsof aerosol and the use of this practice
duringproductionshould be discouraged.If cleaningis essential during
production,methodsthat produce the leastgeneration of aerosols shouldbe
considered, for example using a `scraper blade'or clothmay be adequate and
produce far less aerosol thanhosing.
∑ Compressedair linesare sometimesusedto dislodgecontaminationand this
can also generateaerosols (Holahet al., 2004).The use of this practice during
production should also be discouraged.
∑ Avoidareasin equipmentdesignwhere watercould collect, for example, in
the reel casingof a retractable hose.
∑ Providefacilitiesfor the disposalof waterfromcleaning operationssuchas
the washwaterfromthe tankof a mechanical floorscrubber.
Theseare just examples that illustratethe general principles of good design and
operation of opencleaningoperations.Obviously, factory layoutand operation
can also havea verysignificantimpacton the dispersalof aerosolsand again
goodpractice is essential. Ensuringthat cleaningis wellaway fromproduction
and that bothproduct and packagingare exposed for onlyshortperiodsare
Aerosolsas a contamination risk 99