be providedwithone door,usuallythe external dooron an external porch,
being solid,and the internal doorbeinga flyscreen door;on an internal porch
it wouldbe the opposite configuration.Air jets directed overdoorways,
designedto maintain temperature differentialswhenchiller/freezerdoorsare
opened, mayhavea limitedeffecton controllingpest access.
∑ The sitingof factory openings shouldbe designedwithdue considerationfor
prevailingenvironmental conditions,particularlywinddirectionand drainage
falls.
∑ Whereverpossible, buildings should be singlestorey or withvaryinghead-
room, featuring mezzaninefloorsto allowgravity flowof materials,where
this is necessary. This preventsany movementof wastes or leakingproduct
movingbetween floors.
∑ In addition,drainagesystemshavebeenobserved to act as air distribution
channels, allowingcontaminatedair movement betweenrooms.Thiscan
typically occurwhenthe drainsare littleusedand the watertrapsdry out.
∑ For manyfoodmanufacturersand retailers, glassis seenas the second major
foodhazardafter pathogenic microorganisms.For this reason,glass should be
avoided as a construction material (windows, inspectionmirrors,instrument
and clockfaces,etc.).If used,e.g. as viewingwindows to allowvisitor or
managementobservation, a glassregister,detailing all typesof glassusedin
the factory, and theirlocation,should be composed.
∑ Windowsshould eitherbe glazedwithpolycarbonateor laminated. Where
opening windows are specifically usedfor ventilation(particularly in tropical
areas), thesemust be screenedand the screensbe designedto withstand
misuseor attemptsto removethem.Flyscreens shouldbe constructed of
stainless steelmeshand be removable for cleaning.
∑ If a filteredair supplyis requiredto processing areasand the supplywill
involveducting, a minimum levelof filtration of >90%of 5m particles is
required, e.g. G4 or F5 filters(BS EN 779),to provideboth suitablyclean air
and preventdustaccumulationin the ductwork.
Within the internalenvironment, most factoriesare segregatedinto foodpro-
duction areas (raw material storage, processing, final product storage and
dispatch)and amenities (reception, offices, canteens, trainingrooms,engineering
workshops,boilerhouses,etc.). The primereasonfor this is to clearly separate the
foodproduction processes fromthe otheractivities that the manufacturermust
perform.Thismay be to controlmicrobiological or foreignbodyhazardsarising
fromthe amenityfunctions,but is alwaysundertakento fostera `youare now
entering a foodprocessingarea' hygienicmentalityin foodoperatives.
Food productionareas are typically segregated into raw material intake,raw
material storage, processing, packaging and final product warehouse and
dispatch.In addition,the flowof ingredients and productsis suchthat,in ideal
conditions,raw materials enter at one end of the factory (dirty end)and are
dispatchedat the opposite end (cleanend).Othergoodbasicdesign principles
given by Shapton and Shapton (1991)are:
152 Handbookof hygiene controlin the foodindustry