In a laboratory hood system having a housing with an access window openinginto an interiorwork chamber for performing laboratory processes, and an air circulationsystem for creating anair flow from the laboratory environment inwardly through the access windowinto the workchamber for preventing hazardous materials from escaping into the laboratoryenvironmentthrough the access window, one or more air intake control devices are disposedin a selectedlocation or locations at the access window to overcome any tendency for airturbulence to occur.The air intake control device has an air flow channel extending from an airintake opening to thelaboratory environment to an air discharge opening to the work chamber, with aconstriction inthe channel for causing a venturi-effect increase in air velocity whileflowing through thechannel to promote non-turbulent air flow entering the work chamber at theselected location orlocations.
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