The use of proper procedures and equipment cannot be overemphasized in providing primary personnel and environmental protection. The Biosafety Cabinet (BSC) is not a substitute for appropriate laboratory practice and proper aseptic technique. Aerosols can escape with poor laboratory procedures & methods. Chemical vapors will pass through HEPA filters, and most biological safety cabinets do not protect from volatile toxic chemicals or radionuclides. When working with harmful aerosols or vapors it is required to use a Class II, Type B2 Biological Safety Cabinet that exhausts all air through the facility's house exhaust system.