Design criteria for laboratories – General Laboratory Design: Providing a basic level of safety design for the handling of Low-Intermediate toxicity compounds.
In order to ensure that a potentially hazardous environment within the Laboratory does not affect areas outside the designated laboratory, a negative differential air pressure relative to the surrounding areas is recommended. Laboratory room air pressures should be maintained between 5 and 12.5 Pascals (0.02 to 0.05 inches of water column) below the pressures in the corridor outside the laboratory and also adjacent rooms.
Maintaining a negative environment in the laboratory relative to the outside will protect areas immediately outside the laboratory.
However, in order to provide basic protection for staff within the laboratory the actual air within the laboratory should be extracted and replaced with clean air from outside (i.e., single-pass air). An air change rate between 12 and 15 changes per hour should be achieved.
Storage of all chemical reagents and solvents should also be controlled in order to prevent the build-up of hazardous concentrations of vapour, and that in the event of fire chemical storage cabinets provide fire protection for up to 90 minutes allowing safe evacuation and minimizing explosion risks both to emergency service personnel and risk of contamination to the surrounding environment.
ADDITIONAL DESIGN FEATURES FOR CATEGORY 3 – POTENT DRUG HANDLING
Room airlocks/anterooms should be considered to minimize the risk of the laboratory environment contaminating other areas as staff enter and leave the laboratory.
Visual indication that room pressure is maintained, such as a magnehelic pressure gauge situated near the laboratory entrance. This will give staff an indication of the room safety conditions before entering into the laboratory.
ADDITIONAL DESIGN FEATURES FOR CATEGORY 4 – HIGHLY POTENT DRUG HANDLING
A separate HVAC (Heating Ventilation and air Conditioning) system is recommended. This will isolate the laboratory from any other area of the facility in case of contamination.
A negative differential air pressure relative to the surrounding environment is essential.
Room airlocks/anterooms are required for laboratory areas that maintain a negative room pressure.
An alarm/monitoring system is strongly advised to alert operators to the failure of the air pressurization system. This would commonly be linked to a Building Management System.
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