Table of Contents
I. What Are Welding Fumes?
1.1 Welding Fume Composition
1.2 Types of Welding Processes
II. Risks and Health Hazards of Welding Fumes
2.1 Who Is at Risk of Exposure to Welding Fumes?
2.2 What Are the Health Effects of Welding Fumes?
III. Exposure Standards and Classifications
IV. How to Control Exposure to Welding Fumes
V. Atmospheric Monitoring
VI. Health Monitoring
VII. FAQs
Conclusion
I. What Are Welding Fumes?
Welding fumes are a complex mix of fine airborne particles and gases formed during welding, cutting, or heating of metals. When the metal is heated above its boiling point, its vapor condenses into tiny solid particles, often less than 1 micron in diameter. These particles can easily penetrate deep into the lungs.
The composition and toxicity of welding fumes depend on the base metal, filler wire, shielding gas, and surface coatings involved in the process. Even short-term exposure can cause discomfort, while chronic exposure may lead to severe or irreversible health effects.
1. Welding Fume Composition
According to WorkSafe Victoria and CCOHS, welding fume typically contains a combination of:
Iron oxide (Fe₂O₃): Common in steel welding; can irritate the respiratory system.
Manganese (Mn): Excessive exposure can affect the nervous system, leading to coordination or mood disorders.
Chromium (Cr) and Nickel (Ni): Found in stainless steel fumes; both are classified as human carcinogens (IARC Group 1).
Zinc oxide (ZnO): Generated from galvanized steel; causes acute “metal fume fever.”
Copper (Cu), Aluminum (Al), and Titanium (Ti) oxides: Produced in various alloy welding applications.
Fluorides: Released from fluxes used in some electrodes and flux-cored wires.
Silica and Aluminum oxide dusts: From coated materials or filler metals.
In addition to particulates, harmful gases are also produced:
Ozone (O₃): Generated by the ultraviolet light from electric arcs, particularly in TIG or MIG welding.
Carbon monoxide (CO): From incomplete combustion of shielding gases.
Nitrogen oxides (NO and NO₂): Produced by high-temperature reactions with atmospheric nitrogen.
Phosgene and hydrogen chloride: May form if chlorinated solvents or paints are present on the workpiece.
2. Types of Welding Processes
Different welding processes emit fumes at different rates and with varying compositions:
| Process | Fume Generation Level | Typical Fume Components | Gas Emissions |
|---|
| Shielded Metal Arc Welding (SMAW / Stick) | High | Iron, manganese, fluorides | CO₂, CO, ozone |
| Gas Metal Arc Welding (GMAW / MIG) | Medium | Iron, manganese, nickel | Ozone, nitrogen oxides |
| Flux-Cored Arc Welding (FCAW) | High | Iron oxide, fluorides, silica | CO₂, ozone |
| Gas Tungsten Arc Welding (GTAW / TIG) | Low | Minimal metal fume | Ozone, nitrogen oxides |
| Laser and Plasma Welding | Low to Medium | Metal vapors | Ozone, CO, NOx |
| Resistance Spot Welding | Very Low | Negligible particles | Ozone formation possible |
Key takeaway: even “low-fume” processes can produce significant ozone or gas hazards, especially in poorly ventilated or enclosed spaces.
II. Risks and Health Hazards of Welding Fumes
1. Who Is at Risk of Exposure to Welding Fumes?
The people most at risk include:
Professional welders and apprentices regularly performing welding tasks.
Maintenance and repair workers conducting occasional welding.
Supervisors, inspectors, and helpers working close to active welders.
Personnel in confined spaces, ship hulls, tanks, or poorly ventilated workshops.
Note: Even short-duration exposure can exceed safe limits if controls are absent, especially when welding coated, oily, or contaminated metals.
2. What Are the Health Effects of Welding Fumes?
Short-Term (Acute) Health Effects
Eye, nose, and throat irritation from gases and fine particles.
Metal Fume Fever: A flu-like illness caused by inhaling zinc or copper fumes; symptoms include fever, chills, and nausea.
Dizziness or headaches: Caused by high levels of carbon monoxide or ozone.
Nausea and fatigue: Often due to inadequate ventilation in confined spaces.
Long-Term (Chronic) Health Effects
Lung damage and chronic bronchitis: Repeated irritation leads to long-term respiratory issues.
Pneumoconiosis: Accumulation of iron or other oxides in the lungs.
Manganism: Neurological disorder caused by prolonged manganese exposure, resembling Parkinson’s disease.
Kidney and liver impairment: From heavy metal accumulation.
Cancer: Welding fumes and UV-generated gases are recognized by the IARC (2017) as carcinogenic to humans (Group 1). Chromium VI and nickel compounds pose the highest risk.
III. Exposure Standards and Classifications
Authorities worldwide set occupational exposure limits (OELs) to minimize health risks.
| Substance / analyte | Australia (WES / recent guidance) | US (OSHA / ACGIH / NIOSH guidance) | Key note / why it matters |
|---|
| Total welding fumes (not otherwise classified) | 1.0 mg/m³ — 8-hr TWA (WES; reduced from 5 → 1 mg/m³). Jurisdictions are implementing; check your regulator for timing. | No single unified OSHA PEL for "total welding fume" — US practice is to control specific components (Fe, Mn, Cr(VI), Ni, etc.). ACGIH does not have a single “total welding fume” TLV either. (Control by components.) | Major change in Australia — requires re-evaluation of controls and monitoring. |
| Iron oxide (Fe₂O₃, as Fe) | Use the WES/WEL list — typical guidance historically 5 mg/m³ (as Fe) for respirable fraction; check current WES/WEL list for final value in your jurisdiction. | OSHA historically ~10 mg/m³ (fume / total dust); ACGIH TLV (respirable): 5 mg/m³ (ACGIH TLV listed as 5 mg/m³ respirable). | Iron oxide is the biggest mass fraction of most steel fumes — used as a comparator for nuisance dust/fume exposure. |
| Manganese (Mn) | Draft / recommended values (Safe Work Australia review): respirable 0.02 mg/m³; inhalable 0.1 mg/m³ (these are the recommended protective benchmarks in the WES review / evaluation documents). Check final WES/WEL listing for adoption date. | ACGIH TLV (2024 update): respirable 0.02 mg/m³; inhalable 0.1 mg/m³ (ACGIH updated values). OSHA has older PELs or regulates by compound type; NIOSH discusses neurological risk and gives recommendations. Use ACGIH/NIOSH for conservative guidance. | Manganese causes cumulative neurotoxicity — respirable fraction is especially relevant. |
| Chromium (hexavalent Cr(VI)) | Australia: follow WES/WEL specific listing for Cr(VI) compounds — Safe Work Australia references Cr(VI) as a high-risk carcinogen and exposure standards are very low. (Check the WES table for the precise numeric value for the listed Cr(VI) compound). | OSHA PEL for Cr(VI): 0.005 mg/m³ (5 µg/m³) - regulated under 29 CFR 1910.1026. ACGIH and some guidance documents recommend even lower TLVs (ACGIH has driven very low recommended values for Cr(VI)). | Cr(VI) is a confirmed human carcinogen — strict controls and monitoring required (welding stainless steel is a common source). |
| Nickel compounds (as Ni) | Check the WES/WEL list for the specific nickel compound — Safe Work Australia WES list includes nickel values; many jurisdictions treat soluble and insoluble compounds separately. (Refer to the WES table). | ACGIH TLVs vary by form: e.g., some values are 0.1–0.2 mg/m³ (inhalable) for certain compounds; OSHA PELs vary by compound (some older PELs are higher). Use the specific compound’s limit (Ni metal vs soluble vs insoluble). | Nickel compounds are carcinogenic in some forms — identify the specific compound in your process and use that standard. |
| Ozone (O₃) | No Australia-specific WES unique to welding on the Safe Work Aus welding page — treat ozone as a hazardous gas and consult the WES/WEL table for O₃. | OSHA PEL: 0.1 ppm (8-hr TWA); ACGIH TLV varies with workload (commonly 0.05–0.1 ppm TWA depending on work intensity); NIOSH/OSHA methods and IDLH apply for higher exposures. Ozone is commonly formed by arc UV and can reach harmful levels in enclosed spaces. | Ozone is produced by arc UV; even "low-fume" processes can produce ozone in enclosed spaces — monitor where TIG/MIG arcs are used. |
| Nitrogen dioxide (NO₂) / NOx | No single WES for “welding NOx” on Safe Work Aus welding page — consult WES/WEL list for NO₂. SafeWork NSW highlights NOx as a welding gas hazard. | ACGIH TLV (NO₂): 0.2 ppm (TWA); NIOSH REL and other agencies recommend conservative short-term limits (e.g., NIOSH 1 ppm short term guidance). OSHA historically had larger ceiling values; refer to current OSHA tables/methods. | NOx are produced by high-temperature reactions with air and can irritate lungs; STELs are useful to manage short peaks. |
IV. How to Control Exposure to Welding Fumes
WorkSafe Victoria and SafeWork NSW emphasize the hierarchy of control approach:
1. Elimination and Substitution
Use alternative joining techniques (e.g., bolting, riveting) where feasible.
Select low-fume electrodes or solid wires with clean shielding gases.
Remove paints, oils, or galvanizing from work surfaces before welding.
2. Engineering Controls
Local Exhaust Ventilation (LEV): The most effective measure—capture fumes at the source using hoods or extraction arms.
General Ventilation: Improve overall airflow using fans or mechanical systems.
Isolation: Use welding booths or automated enclosures to separate workers from fume sources.
Fume Extraction Guns: Integrate extraction directly into the welding torch for mobile work.
3. Administrative Controls
Limit exposure time through job rotation.
Schedule high-fume tasks when fewer workers are present.
Train welders in correct work positioning and hazard recognition.
Maintain all extraction systems regularly and verify their effectiveness.
4. Personal Protective Equipment (PPE)
Use respiratory protective devices (RPDs)—such as powered air-purifying respirators (PAPR) or disposable masks with P2 or P3 filters.
Wear flame-resistant clothing, leather gloves, and auto-darkening helmets with proper face seals.
Ensure PPE is fit-tested and maintained according to manufacturer and safety standards.
V. Atmospheric Monitoring
Monitoring airborne contaminants helps assess whether exposure limits are being met.
Common Methods:
Personal Sampling: Measures the concentration of fumes a welder inhales during a work shift.
Static or Area Sampling: Evaluates the general environment in a workshop or fabrication hall.
Direct-Reading Instruments: Detect gases like CO, O₃, and NOx in real-time.
WorkSafe Victoria recommends regular monitoring whenever:
New materials or processes are introduced.
Ventilation systems are modified.
Workers report symptoms of fume exposure.
Data collected should be interpreted by qualified occupational hygienists, ensuring compliance with regulatory exposure standards.
VI. Health Monitoring
Health surveillance is essential when workers are exposed to hazardous fumes or metals that can cause chronic effects.
Key Health Monitoring Activities:
Baseline medical assessments before starting welding work.
Periodic lung function (spirometry) tests.
Blood or urine tests for manganese, nickel, or chromium exposure when relevant.
Symptom questionnaires to identify early respiratory or neurological changes.
If results indicate elevated exposure or health deterioration, employers must take corrective actions immediately, such as improving ventilation or changing work practices.
VII. FAQs
Q1: Are welding fumes harmful even when welding outdoors?
Yes. Outdoor welding may reduce accumulation, but wind shifts and poor positioning can still cause high localized exposure. Proper respirators and extraction systems are still advised.
Q2: What’s the best method to reduce fume exposure?
Use local exhaust ventilation (LEV) close to the arc, remove coatings before welding, and wear certified respiratory protection.
Q3: How often should air monitoring be performed?
At least annually, or whenever significant changes in materials, processes, or ventilation systems occur.
Q4: Can certain gases form without visible smoke?
Yes. Ozone, carbon monoxide, and nitrogen oxides are invisible yet highly toxic gases commonly produced during welding.
Q5: What are the early signs of fume overexposure?
Symptoms include headache, metallic taste, coughing, shortness of breath, fever, or unusual fatigue after welding shifts.
Conclusion
Welding fumes and gases are among the most underestimated occupational hazards in fabrication industries. Invisible and often odorless, they can silently harm respiratory, neurological, and even cardiovascular health over time.
By understanding what welding fumes are, implementing engineering controls, and conducting air and health monitoring, employers can ensure that welders breathe cleaner air and work in safer environments.
In 2025, the welding industry continues evolving toward automation, but human safety remains the cornerstone of progress.
▏Clean air, strong lungs, and safe practices—these are the foundations of every good weld.
Related articles
1. Common Dangers of Welding and How to Avoid Them
2. How to Prevent and Control Fire Hazards in Welding Operations?
3. 15 Tips for Improving Welding Safety
4. Welding Safety: Hazards, Tips, & Precautions
5. Navigating Welding Fumes: Hazards, Precautions, and What to Do if Exposed
