This guide describes recommended principles of ventilation to be used in facilities where welding and allied processes are performed. The primary objective of this document is to enhance the health and safety of all those found in a welding environment. Other objectives include the provision of information relevant to energy conservation and environmental compliance. This guide does not provide information on respiratory protection or specific precautions related to working in a confined space. Also@ this guide does not address issues associated with combustible dust hazards applicable to ventilation systems. Information dealing with this issue can be found in NFPA 654@ Standard for Prevention of Fire and Dust Explosions from the Manufacturing@ Processing and Handling of Combustible Particulate Solids@ and NFPA 484@ Standard for Combustible Metals. Basic information related to a range of ventilation systems and techniques that can be used in a welding and cutting environment is provided here. Comparisons are drawn between techniques and highlight both the effectiveness and relative cost of each approach. It is intended that this information will assist in the identification and selection of an appropriate ventilation solution for a specific welding and/or cutting operation.