Artem Komarov noted that welding aluminum produces hazardous fumes that can harm the entire body, including the brain and nervous system. How strong is the exposure to welding fumes? And how can shops reduce the risks of exposure to welders?
Here’s what welders and welding companies need to know about the dangers of aluminum welding.
Composition of fumes from aluminum welding
Thermal processes such as welding produce very small (submicron) particles that can be inhaled into the lungs and absorbed into the body through the respiratory system. While all welding fumes are dangerous if inhaled, specific health risks depend on the composition of the smoke. The base materials and filler metals used determine the composition of the welding fume. When welding non-ferrous metals, the high temperature of the welding process leads to the formation of a mixture of metal oxides; fuming, non-oxidized metal particles; protective gases; and ozone.
Fumes from aluminum welding contain fuming particles of aluminum and aluminum oxide along with other metals used in the alloy, including copper, zinc, magnesium, silicon, manganese, and lithium. While some smoke is emitted from the base metal, a significant amount comes from the consumables used in the welding process.
For aluminum welding, tungsten inert gas (TIG) or metallic inert gas (MIG) is commonly used. Each method will produce different types of fumes and pose different health risks:
— Most of the fumes from MIG welding come from consumables. Non-ferrous consumables usually contain other substances such as silicon, magnesium, zinc, or other trace elements.
— TIG welding uses tungsten welding rods, which create respirable fuming tungsten during the welding process.
MIG and TIG welding of aluminum also generates high levels of ozone, resulting from the reaction between the ultraviolet radiation generated by the welding arc and the oxygen in the air. When welding aluminum using aluminum filler with silicon, a high level of ozone is usually produced. Aluminum welding fumes may also contain other gases including carbon dioxide, carbon monoxide and nitrogen dioxide.
Health risks associated with exposure to aluminum welding fumes.
Exposure to fuming aluminum and its oxides can cause both acute and chronic conditions ranging from lung disease to damage to the nervous system. Acute symptoms of exposure to aluminum welding fumes include:
— Irritating to eyes, nose, throat, and lungs.
— Metal fume fever, an acute influenza-like illness caused by the inhalation of metals and their oxides. Symptoms include cough, chills, and muscle pain.
Long-term exposure can lead to several chronic diseases:
— Lung problems may include occupational asthma; chronic obstructive pulmonary disease (COPD); Chronical bronchitis; and aluminosis, an incurable lung disease that causes permanent scarring of the lungs (fibrosis).
— Aluminum has also been linked to neurodegenerative disorders and brain diseases such as Alzheimer’s, Parkinson’s, and multiple sclerosis, although the role of aluminum or aluminum oxide exposure in these diseases needs further study.
— Manganese, commonly found in MIG welding fumes, is known to cross the blood-brain barrier and can lead to manganese, a neurodegenerative disease like Parkinson’s disease. Symptoms include trembling, difficulty walking, and facial spasms.
— Exposure to tungsten in TIG welding can lead to pulmonary fibrosis; irritation of the eyes, skin, nose and respiratory tract; nausea; and reproductive effects.
Exposure to ozone from aluminum welding has both short-term and long-term health effects. Short-term effects include eye, nose, throat, and lung irritation; headache; and temporary decrease in lung function. Long-term health effects of ozone exposure include asthma and chronic lung disease.
What about fire risks?
In addition to the health effects of welding fumes, companies may also need to consider possible combustion risks. Weld fumes are generally considered non-flammable because the material is already oxidized during the welding process. However, scientific studies have shown that in many cases welding fumes contain a mixture of both oxidized and non-oxidized material. Unoxidized aluminum dust is highly explosive under the right conditions. For this reason, it is generally recommended that welding fumes be tested to determine their explosiveness, including Kst and Pmax values (known as explosion indices). If welding fume is found to be combustible, appropriate precautions must be taken when designing the dust collection system.
Development of a Welding Fume Control Strategy
It is important to have a control strategy in place due to the risks associated with exposure to inhaled metals and metal oxides when welding non-ferrous metals.
Air quality testing and monitoring
The first step in developing a strategy to reduce exposure to welding fumes should be to determine current exposure levels. Testing should also be used to test systems after they have been installed. Air quality testing may include one or both of the following:
— Air quality meters or sensors for measuring particulate matter and gaseous emissions at various installation locations.
— Wearable exposure monitors to determine the exposure levels of people during their normal shift activities.
Dust collection and ventilation systems
Avoiding aluminum and welding rods is usually not an option. This means that technical controls such as dust collection and ventilation are usually the first line of defense against hazardous emissions from aluminum welding.
Whenever possible, specialists prefer a system for capturing the source of welding fume. These systems trap vapors close to the source, keeping them out of the breathing area and preventing them from spreading through the equipment:
— For manual welding, the system must direct the fumes away from the welder’s face. For small parts, repositioned chimneys and welding stations with return or side outlet are usually used. For MIG welding, fume guns attached directly to the welding torch are another option.
— Robotic welding should be covered with a hood if possible. The design of the hood is very important to the overall efficiency of the system. The less air that needs to be moved, the less energy is required to capture the smoke.
In most cases, the source capture system will be connected to an industrial dust collector that filters contaminants from the air for removal and returns clean, filtered air to the site. If capturing the source is not possible (for example, due to the size of the parts or the use of overhead cranes), welding fumes can be controlled using general ventilation or an environmental dust collection system. The air conditioning system must be designed to remove fumes from where people work and return clean, fresh air to the work area to dissolve contaminants to a safe level. For both source capture and environmental capture, filtering the air with a dust collector is preferable to simply venting polluted air to the outside, which can lead to environmental violations in the enterprise.
If welding fumes are determined to be combustible, the dust collection system must be equipped with appropriate fire and deflagration protection systems to reduce the risk of a dangerous explosion inside the manifold or ducts. The system must comply with OSHA regulations and National Fire Protection Association guidelines for fire and explosion safety.
Protecting welders from hazardous emissions should be a priority for aluminum welding shops. While the principles of fumes safety remain basically the same for all materials, it is helpful to understand the specific risks associated with the materials you are working with. Once you understand the risks and exposure limits, you can develop a system that will protect everyone from hazardous welding emissions, summed up Komarov Artem.