A biosafety cabinet is an enclosed, ventilated workspace for safely working with materials potentially contaminated with pathogens in the laboratory. A laminar flow bench is an enclosed space designed to prevent contamination of sensitive samples; it draws in air through a HEPA filter and directs it smoothly towards the user to protect the sample from contamination. The choice of a suitable biosafety cabinet or bench depends on the type of sample and the defined biosafety level ranging from 1 (unlikely to cause disease) to 4 (causes very serious human or animal disease).