Ventilation in welding operations

Mechanical ventilation can be either a general mechanical ventilation system or a local exhaust system. See 1926.353(a)(1).

• General ventilation moves large volumes of air through a space to dilute welding fumes; local exhaust uses movable hoods placed close to the source to capture fumes before they reach the welder's breathing zone. See 1926.353(a)(2) and 1926.353(a)(3).

• Choose the system that will keep fumes and smoke in the breathing zone within the safe limits in Subpart D of Part 1926.

General mechanical ventilation is sufficient when it produces the number of air changes needed to keep welding fumes and smoke within the safe exposure limits in Subpart D of Part 1926. See 1926.353(a)(2).

• Verify adequacy by measuring contaminant levels against the permissible exposure limits in Subpart D and by confirming appropriate air-change rates for the workspace.
• If monitoring shows exposures above limits, increase ventilation, switch to local exhaust, or provide appropriate respiratory protection.

Local exhaust ventilation must use freely movable hoods that the welder or burner can place as close as practicable to the work. See 1926.353(a)(3).

• Position the hood as near the arc or molten pool as possible without interfering with the operation to capture fumes at the source.
• Ensure the system has sufficient capture velocity and capacity to remove fumes from the breathing zone; if it does not, provide additional controls or respiratory protection.

Contaminated air exhausted from the workspace must be discharged into the open air or otherwise away from the intake source, and the air replacing that withdrawn must be clean and respirable. See 1926.353(a)(4) and 1926.353(a)(5).

• Do not vent exhaust so it can be drawn back into the building or into another worker's breathing zone.
• Make sure make-up air does not come from contaminated areas and is suitable for breathing by workers.

No — oxygen must not be used for ventilation, comfort cooling, blowing dust from clothing, or cleaning the work area. See 1926.353(a)(6).

• Use only air (or other approved breathable replacement air) for ventilation and make-up air; oxygen enrichment can create a fire and explosion hazard around welding operations.

Yes — except where paragraphs (b)(2) and (c)(2) apply, either general mechanical ventilation or local exhaust meeting paragraph (a) must be provided whenever welding, cutting, or heating is done in a confined space. See 1926.353(b)(1).

• Confined spaces often concentrate fumes and gases, so provide approved ventilation to keep exposures within limits or use approved respiratory protection when ventilation cannot reduce exposures adequately.

If sufficient ventilation cannot be obtained without blocking means of access, employees in the confined space must be protected by air line respirators and an attendant outside must maintain communication and be ready to aid in an emergency. See 1926.353(b)(2).

• Assign a trained attendant outside the space to observe and assist workers, and ensure communication systems are reliable.
• The use of air line respirators must meet the respiratory-protection requirements in Subpart E of Part 1926 (see 1926SubpartE).
• Employers should perform a hazard assessment before selecting respirators; see OSHA's guidance on PPE hazard assessments in the letter of interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28.

When a welder must enter through a manhole or small opening, employers must provide means to quickly remove the welder in an emergency; when using safety belts and lifelines, they must be attached so the welder's body cannot be jammed in the exit opening. See 1926.353(b)(3).

• Use retrieval systems or harnesses designed for confined-space rescue, and train attendants and rescue personnel in pre-planned rescue procedures.
• Coordinate these provisions with the attendant requirement in 1926.353(c).

Welding, cutting, or heating in enclosed spaces involving zinc-bearing, lead-base, cadmium-bearing, or chromium-bearing metals (including their coatings) must be performed with general or local mechanical ventilation meeting paragraph (a). See 1926.353(c)(1) and its subparts: 1926.353(c)(1)(i), 1926.353(c)(1)(ii), 1926.353(c)(1)(iii), and 1926.353(c)(1)(iv).

• These metals can generate toxic fumes; where ventilation alone cannot keep exposures below limits, provide appropriate respiratory protection per Subpart E.

For enclosed-space operations with metals listed in 1926.353(c)(2) employers must use local exhaust ventilation in accordance with paragraph (a) or protect employees with air line respirators; beryllium work requires both local exhaust ventilation and air line respirators. See 1926.353(c)(2) and its specific items 1926.353(c)(2)(i) through 1926.353(c)(2)(iv).

• For beryllium-containing base or filler metals, both engineering (local exhaust) and supplied-air respiratory protection are mandatory because of its high toxicity.
• Respirator selection and use must comply with Subpart E of Part 1926; perform a hazard assessment to choose the correct respirator (see OSHA interpretation on PPE hazard assessment at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28).

Employees performing such operations in the open air must be protected by filter-type respirators under Subpart E, except for beryllium work where air line respirators are required; other employees exposed to the same atmosphere must be protected the same way as the welder or burner. See 1926.353(c)(3) and 1926.353(c)(4).

• Ensure filter-type respirators are appropriate for the contaminant and properly fitted; for beryllium, use air line respirators even outdoors.
• Respirator programs, medical evaluations, and fit testing must follow the requirements in Subpart E of Part 1926 (see 1926SubpartE).

Employees must not be exposed to inert-gas metal-arc welding until special precautions are taken because the process produces intense ultraviolet radiation and can decompose chlorinated solvents and liberate toxic fumes. See 1926.353(d).

• Specific precautions include separation or shielding of chlorinated solvents (see 1926.353(d)(1)(i)), eye and skin protection (see 1926.353(d)(1)(ii)-(iii)), and extra measures when welding stainless steel to control nitrogen dioxide exposures (1926.353(d)(1)(iv)).

Chlorinated solvents must be kept at least 200 feet from an exposed inert-gas welding arc unless the solvent residue is shielded. See 1926.353(d)(1)(i).

• Surfaces prepared with chlorinated solvents must be thoroughly dry before welding on them.
• If you cannot keep the solvent that far away, provide shielding or other controls to prevent solvent decomposition and toxic gas formation.

Employees not protected by screening must be protected by filter lenses that meet Subpart E requirements, and welders must fully cover skin to prevent burns and other ultraviolet damage. See 1926.353(d)(1)(ii) and 1926.353(d)(1)(iii).

• When multiple welders are exposed to each other's arcs, wear filter-lens goggles under welding helmets as described in 1926.353(d)(1)(ii).
• Use hand shields when helmets are lifted; ensure helmets and shields meet Subpart E eye-protection requirements (see 1926SubpartE).

When inert-gas metal-arc welding is done on stainless steel, employers must meet the requirements of 1926.353(c)(2) to protect against dangerous concentrations of nitrogen dioxide. See 1926.353(d)(1)(iv).

• That means using local exhaust ventilation or providing appropriate supplied-air respirators as required in 1926.353(c)(2).
• Monitor air for nitrogen dioxide and follow Subpart E respirator rules if ventilation does not keep exposures below limits.

If unusual physical or atmospheric conditions cause an unsafe accumulation of contaminants during general welding, cutting, or heating, the employer must provide suitable mechanical ventilation or respiratory protective equipment. See 1926.353(e)(1).

• Employers should monitor the workplace and otherwise assess hazards; if ventilation will not reduce exposure below limits, provide appropriate respirators per Subpart E.
• Perform a PPE hazard assessment and document it when respiratory protection will be used (see OSHA interpretation on PPE hazard assessment at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28).

All employees performing welding, cutting, or heating must be protected by suitable eye protective equipment in accordance with Subpart E of Part 1926. See 1926.353(e)(2).

• Select filter lenses or goggles appropriate to the welding process and exposure level, and provide training and fitment per the eye-protection requirements in Subpart E (1926SubpartE).

Welding helmets and hand shields must be free of leaks and openings and must not have highly reflective surfaces. See 1926.353(d)(1)(ii) and 1926.353.

• Inspect helmets and shields regularly for cracks, holes, or reflective surfaces that could increase glare or radiation exposure.
• Replace or repair equipment that does not meet these requirements to maintain eye and face protection integrity.

No — for beryllium-containing base or filler metals, work must be done with both local exhaust ventilation and air line respirators; filter-type respirators are not sufficient. See 1926.353(c)(2)(iv) and 1926.353(c)(2).

• Because of beryllium's high toxicity, employers must provide engineering controls plus supplied-air respiratory protection that meets Subpart E requirements.

Other employees exposed to the same atmosphere as the welders or burners must be protected in the same manner as the welder or burner. See 1926.353(c)(4).

• Do not assume adjacent workers are safe just because they are not welding; assess their exposures and provide the same ventilation and respiratory protection required for the welder when necessary.

Employers should assess workplace hazards and exposures to determine whether respirators are needed and, if so, select appropriate respirators that meet Subpart E requirements. See 1926SubpartE and consult OSHA's PPE hazard assessment guidance at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28.

• The hazard assessment should identify contaminants, exposure levels, and tasks that might require respiratory protection, and the employer must implement a respiratory program when respirators are used.
• Document the assessment and follow medical evaluation, fit testing, and training requirements in Subpart E.