Welding, Cutting & Compressed Gas
Welding Respiratory
Hazards — Fumes & Gases
Hazards — Fumes & Gases
OSHA 1910.1000 · ACGIH TLVs · Mn: 0.02 mg/m³ · Local Exhaust Ventilation Preferred
Welding fumes are not just smoke — they are a complex mixture of metallic oxides, silicates, and gases at concentrations that can exceed OSHA limits within seconds in a confined or poorly ventilated area. Manganese in welding fumes causes Parkinson's-like neurological damage. Hexavalent chromium from stainless steel welding causes lung cancer. These are not theoretical risks — they are occupational diseases affecting ironworkers and welders across NYC.
The Primary Respiratory Hazards by Material
- Mild steel: Iron oxide fumes, manganese (Mn). OSHA PEL for Mn: 5 mg/m³ (ACGIH TLV: 0.02 mg/m³ — 250 times stricter than OSHA). Chronic Mn exposure causes manganism
- Stainless steel / chrome alloys: Hexavalent chromium (Cr VI) and nickel compounds. Cr VI is a Group 1 IARC carcinogen — proven to cause lung cancer. OSHA 29 CFR 1926.1126 governs stainless welding
- Coated materials (galvanized, painted): Zinc fumes (metal fume fever), lead fumes (from lead paint), and coating-specific products. Never weld coated materials without knowing what the coating contains
- Gases: Ozone from TIG/MIG arcs, nitrogen oxides, carbon monoxide from incomplete combustion
Engineering Controls — In Order of Preference
- Local exhaust ventilation (LEV) at the source: a capture hood within 12 inches of the welding arc removes fumes before they enter the breathing zone
- General ventilation: minimum 2,000 CFM per welder — calculate the volume of the space and the required air changes
- Respiratory protection: a last resort when ventilation is insufficient — P-100 filter for metal fumes; OV/P-100 combination for organic gases
Confined Space Welding on NYC Sites
- Welding inside tanks, vessels, crawl spaces, or partially enclosed rooms requires continuous air monitoring and a separate confined space entry permit
- Local exhaust is required — the confined space must be continuously purged
- Never weld inside a confined space in NYC without the CSFSM's review and permit authorization
Discussion Questions
- What neurological condition is caused by chronic manganese exposure from welding fumes?
- You need to cut sections of stainless steel framing with a plasma cutter. What specific hazard does this create beyond regular welding fumes?
- What is the engineering hierarchy of controls for welding fumes, from most preferred to least?
- A welder says they feel fine and don't need ventilation "for just a few welds." What is the response to this?
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