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Health risks associated with inhalation of fume particles

Welder Health · Airborne Particles Health Risks Associated With Inhalation of Welding Fume Particles Welding fume contains very small airborne particles that can be inhaled deep into the respiratory system. Exposure has been associated with respiratory disease, metal fume fever, neurological effects from certain metals, and increased cancer risk. Welding fumes are classified by IARC as carcinogenic to humans. Focus Welding Fume Particles Primary Control Source Capture & Ventilation Updated September 2026 Why Are Welding Fume Particles a Health Concern? Welding generates an aerosol made up of gases and very small solid particles. The composition changes depending on the welding process, base material, filler metal, electrode, flux, coatings and other materials involved. Welding fume is important from a respiratory-health perspective because much of the particulate is extremely small. Research supported by NIOSH has found that welding fume contains a significant submicron and nanometer-sized particle fraction. Smaller particles can penetrate deeper into the respiratory tract than larger particles. Where a particle deposits depends on its size, shape and other physical characteristics. More than 700,000 workers in the United States are involved in welding or allied processes, according to census data cited by NIOSH. Source: NIOSH Engineering Controls Database What Is Welding Fume Made Of? Welding fume can contain metal oxides, fluorides and other chemical species. The exact composition depends on the material and welding process. Metals that may be present include: Iron Chromium Nickel Zinc Manganese Cobalt Lead Copper Welding and cutting can also generate gases such as: Ozone Nitrogen oxides Carbon monoxide Carbon dioxide Shielding gases such as argon and helium Different contaminants have different occupational exposure limits and health effects, which is why welding fume should not be treated as one uniform substance. How Small Are Welding Fume Particles? Welding fumes can contain particles ranging from only a few nanometers to many micrometers in diameter. Primary particles are formed close to the welding arc and can be extremely small. Research describing welding-fume aerosols has found that individual particles can initially form in the ultrafine range and then combine into larger agglomerates as they move away from the arc. In one detailed NIOSH-supported characterization, more than 95 percent of welding-fume mass was contained in particles smaller than 1 micrometer. Why this matters: Visible smoke does not represent the entire exposure. A substantial amount of welding-fume particulate can be extremely small and remain suspended in the air. Source: NIOSH-supported Welding Fume Particle Size Research Does Particle Size Affect Where Fume Deposits in the Lungs? Yes. Particle size is one of the factors that determines how far an inhaled particle can travel into the respiratory system and where it may deposit. Welding fume has a broad particle-size distribution. Very small particles can penetrate into deeper regions of the respiratory tract, while larger particles are more likely to deposit earlier or settle onto nearby surfaces. Studies have observed welding-fume particles in the welder's breathing zone in the submicron and low-micrometer range. Welding processes can also generate large numbers of ultrafine particles and nanoparticles. Particle Characteristic What It Means Nanometer and ultrafine particles Can be generated in large numbers close to the welding arc Submicron particles Represent a significant portion of welding-fume aerosol and can penetrate deeply into the respiratory system Agglomerated particles Form when smaller primary particles combine after leaving the welding arc Larger particles and spatter Are more likely to settle onto nearby surfaces, although some larger respirable particles can still be inhaled What Health Effects Are Associated With Welding Fume? Welding-fume exposure has been associated with a range of respiratory and other occupational health effects. The actual risk depends on the contaminants involved, exposure concentration and duration. Respiratory Effects NIOSH identifies health effects associated with welding including pneumonitis, chronic bronchitis and reductions in pulmonary function. Occupational exposure to metal and welding fumes has also been associated with chronic respiratory conditions, including increased risk of COPD in some work environments. Metal Fume Fever Exposure to certain freshly formed metal oxides can produce metal fume fever, an acute illness with flu-like symptoms. Zinc oxide generated when welding galvanized material is one common cause. Manganese and Neurological Effects Most welding fumes contain at least a small percentage of manganese. Inhaled manganese is a concern because prolonged exposure to high airborne concentrations can affect the central nervous system. NIOSH states that prolonged exposure to high manganese concentrations may lead to a Parkinsonian syndrome called manganism. Manganism can produce symptoms that resemble some features of Parkinson's disease, but the two conditions should not be treated as interchangeable. Source: CDC/NIOSH Welding Fumes and Manganese Cancer Risk The International Agency for Research on Cancer classifies welding fumes as Group 1, carcinogenic to humans. IARC found sufficient evidence for lung cancer and limited evidence for kidney cancer in relation to welding-fume exposure. Read more in Welding Fume Classified as Carcinogenic to Humans . Source: International Agency for Research on Cancer What Determines the Level of Welding Fume Risk? Welding-fume risk depends on more than particle size. Three factors are particularly important: Toxicity: Which metals, gases and chemical compounds are present? Concentration: How much contaminant is present in the worker's breathing zone? Exposure duration: How long and how frequently is the worker exposed? The welding process, material, coating, ventilation, number of welders and facility layout can all affect these factors. What About OSHA's 5 mg/m³ Welding Fume Limit? The commonly cited 5 mg/m³ OSHA limit requires some context. OSHA has applied a total welding-fume limit of 5 mg/m³ as an 8-hour time-weighted average for welding involving iron, mild steel or aluminum. However, more protective substance-specific limits apply when particular contaminants such as lead, chromium or other hazardous metals are present. A total-fume measurement therefore does not replace evaluation of the individual hazardous substances generated by a specific welding operation. Source: OSHA Welding Fume PEL Interpretation Why Is the Welding Plume Important? Welding-fume concentration is generally greatest close to the source of generation. If a worker positions their head directly in the rising plume, contaminants can pass through the breathing zone. As the plume moves away from the weld it mixes with surrounding air, but dilution alone should not be assumed to provide adequate control. This is why both work positioning and properly designed ventilation matter. How Does Arc Time Affect Welding Fume Exposure? The amount of time a worker spends actively welding affects how much fume is generated during a shift. A fabricator who spends much of the day fitting and preparing components may have less active welding time than a production welder working continuously on prepared parts. More arc time generally creates more opportunity for exposure, but duration alone does not determine risk. A shorter exposure to a highly hazardous contaminant can still require strict controls. How Can Welding Fume Particle Exposure Be Reduced? Engineering controls are an important part of welding-fume exposure reduction. OSHA requires local exhaust or general ventilation to keep toxic fumes, gases and dusts below applicable exposure limits. Local exhaust ventilation places the capture hood close to the welding operation so contaminated air can be removed before it spreads through the wider workspace. NIOSH recommends reducing welding emissions to the lowest feasible concentrations using engineering controls and work practices. Depending on the application, an overall control strategy may include: Local exhaust ventilation or source capture General mechanical ventilation Keeping the worker's head out of the fume plume Appropriate work practices Exposure monitoring where needed Respiratory protection when required Sources: OSHA 29 CFR 1910.252 and OSHA Welding Fume Control Guidance Frequently Asked Questions Why are welding fumes classified as carcinogenic? IARC classifies welding fumes as Group 1, carcinogenic to humans. Its evaluation found sufficient evidence for lung cancer and limited evidence for kidney cancer. What size are welding fume particles? Welding fume contains a broad range of particle sizes, from nanoparticles only a few nanometers across to particles several micrometers or larger. A substantial portion of welding fume is in the submicron range. Are particles between 1 and 7 μm the most dangerous? Older welding guidance emphasized particles in the 1 to 7 μm range because they can penetrate into the lungs. More recent research shows that welding fumes also contain substantial numbers of submicron and nanoparticles, so particle risk should not be reduced to a single size range. How long can welding fume remain airborne? Small welding-fume particles can remain suspended after welding stops, with persistence affected by particle size, air movement, ventilation and the surrounding environment. Effective ventilation helps remove suspended contaminants instead of allowing them to accumulate. Can manganese in welding fume cause Parkinson's disease? High manganese exposure can cause manganism, a Parkinsonian neurological syndrome with some symptoms similar to Parkinson's disease. It should not simply be described as Parkinson's disease. What is the best way to reduce welding fume exposure? Local exhaust ventilation can capture fumes close to their source before they spread through the workplace. Depending on the application, general ventilation, work practices, exposure monitoring and respiratory protection may also be required. Related Reading How to Protect Your Respiratory Health From Welding Fumes What Is a Welding Fume Extractor? MobileGo vs. MobilePro: Which Fume Extractor Is Right for Your Shop? Welding Fume Facts: What It Is and What It Does to You Need Help Reducing Welding Fume Exposure? Tell us about your welding process, materials and work area. We can help narrow down the extraction options that fit your application. Find the Right System