General welding, cutting, and heating not involving toxic conditions or materials described in the following sections, may normally be done without mechanical ventilation or respiratory protective equipment. Mechanical ventilation or respiratory protective equipment must be used when physical or atmospheric conditions create an unsafe accumulation of contaminants.

7.1 Mechanical Ventilation

For purposes of this section, mechanical ventilation must meet the following requirements:

Mechanical ventilation consists of either general mechanical ventilation systems or local exhaust systems.

General mechanical ventilation must be of sufficient capacity and so arranged as to produce the number of air changes necessary to maintain welding fumes and smoke within safe limits.

Local exhaust ventilation must consist of freely movable hoods intended to be placed by the welder or burner as close as to the work. The hood must be of sufficient capacity and so arranged as to remove fumes and smoke at the source and keep the concentration of them in  the breathing zone within safe limits. If you are uncertain whether your hood meets these criteria, please contact the Environmental Health & Safety Manager for assistance.

Contaminated air exhausted from a working space must be discharged into the open air or otherwise clear of the source of intake air.

Oxygen must never be used for ventilation purposes, comfort cooling, blowing dust from clothing, or for cleaning the work area.

7.2 Welding, Cutting, or Heating Toxic Metals

Welding, cutting, or heating in any enclosed spaces involving the metals specified below must be performed with either general mechanical or local exhaust ventilation:

Zinc-bearing base or filler metals or metals coated with zinc-bearing materials.

Lead base metals.

Cadmium-bearing filler materials.

Chromium-bearing metals or metals coated with chromium-bearing materials.

Metals containing lead, other than as an impurity, or metals coated with lead-bearing materials.

Cadmium-bearing or cadmium-coated base metals.

Metals coated with mercury-bearing metals.

Beryllium-containing base or filler metals. Because of its high toxicity, work involving beryllium must be done with both local exhaust ventilation and air line respirators.

Wearing approved filter-type respirators will protect employees performing such operations without adequate ventilation. Approved air line respirators will protect employees performing such operations on beryllium-containing base or filler metals. Employees who use respirators must follow the policies and procedures in the Respiratory Protection Section.

7.3 Other Employees

Other employees exposed to the same atmosphere as the welders or burners must be protected in the same manner as the welder or burner.