(1) Air replacement. You must adequately ventilate all welding and cutting operations carried on in confined spaces to prevent the accumulation of toxic materials or possible oxygen deficiency. This applies not only to the welder but also to helpers and other personnel in the immediate vicinity. All air replacing that withdrawn must be clean and respirable.

(2) Airline respirators. In such circumstances where it is impossible to provide such ventilation, you must use airline respirators or hose masks approved for this purpose by the National Institute for Occupational Safety and Health (NIOSH) under 42 C.F.R. Part 84.

(3) Self-contained units. In areas immediately hazardous to life, you must use a full-facepiece, pressure-demand, self-contained breathing apparatus or a combination full-facepiece, pressure-demand supplied-air respirator with an auxiliary, self-contained air supply certified by NIOSH under 42 C.F.R. Part 84.

(4) Outside helper. Where welding operations are carried on in confined spaces and where welders and helpers are provided with hose masks, hose masks with blowers or self-contained breathing equipment approved by the Mine Safety and Health Administration (MSHA) and the National Institute for Occupational Safety and Health (NIOSH), a worker must be stationed on the outside of such confined spaces to ensure the safety of those working within.

(5) Oxygen for ventilation. You must not use oxygen for ventilation.