General Industry of welding concerning ventilation for shops. Concerning AS Lewistown weld shop and safety of workers. All hollow spaces or cavities should be vented to allow air and gases to escape before welding is begun. Mechanical ventilation should be required when welding takes place in a space less than 10,000 cubic feet per welder, or in a room with a ceiling height of less than 16 feet. The mechanical ventilation should be at a minimum rate of 2,000 cubic feet per minute per welder. Movable hoods should be placed as close to the welder as is practical. The hood should provide an air flow rate that is sufficient to maintain a velocity in the hood direction of 100 linear feet per minute. Oxygen should not be used for ventilation. In situations where it is impossible to provide adequate ventilation, all workers should wear OSHA-approved airline respirators or hose masks. A shop space of 60ftX60ftX300ft = 1,080,000ft3. As according to the above information there would be fresh air available in that shop space for 540 minutes or 9 hours. The assumption of no fresh air supplied by legal supply air system. Therefore, behond one active welder in the above mentioned shop would not meet OSHA standards.