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over the tissue culture (Fig. 2.1). This mechanism protects the operator and ensures that

the air over the cultures is largely sterile. These hoods are adequate for animal cell

culture, which involves low to moderate toxic or infectious agents, but are not suitable

for use with high-risk pathogens, which may require a higher level of containment.

Class III hoods

Class III safety cabinets are required when the highest levels of operator and product

protection are required. These hoods are completely sealed, providing two glove

pockets through which the operator can work with material inside the cabinet

(Fig. 2.1). Thus the operator is completely shielded, making class III hoods suitable

for work with highly pathogenic organisms including tissue samples carrying known

human pathogens.

Practical hints and safety aspects of using cell culture hoods

All hoods must be maintained in a clutter-free and clean state at all times as too much

clutter may affect air flow and contamination will introduce infections. Thus, as a

rule of thumb, put only items that are required inside the cabinet and clean all work

surfaces before and after use with industrial methylated spirit (IMS). The latter is used

at an effective concentration of 70% (prepared by adding 70% v/v IMS to 30% Milli-Q

Class I Class II

Class III

Room air

Contaminated air

Clean air

Fig. 2.1Schematic representation of tissue culture cabinets.

41 2.2 The cell culture laboratory and equipment