Laboratory techniques may produce aerosols, which can contain hazardous research materials, such as infectious agents that laboratory workers could inhale. Biological safety cabinets (BSC) are one type of primary barrier to contain potentially infectious research materials in order to prevent exposure of laboratory personnel and contamination of the general environment. Some biological safety cabinets also provide a clean work environment to protect cell cultures or sterile apparatus. Discussion of another type of primary barrier, the laboratory hood, is in Chapter 17.