In the years I have spent fusing metals together in my workstation, the wispy white smoke produced during the welding process was something I was accustomed to. When subjected to a high heat, any material produces smoke on combustion; metals are no exception. In welding, metals are subjected to very high temperatures till they reach the melting point producing gases and fumes as byproducts in the process.
To explain further, most welders dismiss the smoke like a normal aspect of their job just like the annoyingly loud noise welding makes and take welding gears and safety measures lightly. But, little do we realize this seemingly normal smoke is loaded with hazardous toxic compounds and metal fumes that could lead to a number of diseases. To make things easier, the hazardous substances present in these fumes can be broadly classified into respiratory damaging substances, toxic substances and carcinogenic substances.
In a report, The Center for Disease Control and Prevention points out that about 11-21 percent of asthma-related deaths are caused due to workplace exposure. It also acknowledges that the welding fumes released in welding, brazing and other related processes put the workers at a higher risk.
Also, safety enforcement and regulatory agencies have set a permissible exposure limit to metal fumes and other regulations to make the practice and the working environment safe for the workers. Above all, it’s important to be aware of the hazards welding fumes present. This is because it will help workers in the field avoid medical complications Being aware of the hazards welding fumes present will help workers in the field to avoid medical complications associated with it by taking the necessary safety measures and precautions.
Health Hazards From Welding Fumes
Exposure to these fumes could have a number of short-term as well as long-term impacts on the health of the worker. For instance, irritation of eyes, nose, throat, nausea and dizziness are some of its short-term effects. Metal fume fever is another short-term illness that may be caused due to exposure to zinc fumes. This fever is usually accompanied with other symptoms like night sweats, shortness of breath, chills, stomach pain and a metallic taste in the mouth. Long term exposure to these toxic metal fumes can put the worker at risk for the following illnesses:
- Stomach ulcer
- Nervous damage
- Asthma, Pneumonia and other lung problems
- Parkinson’s disease
- Skin disease
- Heart disease
- Kidney damage
Furthermore, some studies have even pointed out that welders are at high risk of cancer of the lungs. Apart from the lungs, the carcinogenic substances are also known to affect and cause tumors in the larynx, kidney and bladder. Chrome (VI) compounds, lead oxide, nickel oxide, cadmium oxide, cobalt oxide and formaldehyde are some of the probable carcinogens found in welding fumes.
What Makes Welding Fumes Toxic?
The welding process produces oxides of the metal being welded, some of which are toxic and can be harmful when inhaled. These particles are finer than dust and are absorbed deeply into the respiratory system. So, welding fumes contain a number of airborne metal particles and harmful gases like:
- Zinc Oxide
- Carbon monoxide
- Nitrogen dioxide
- Nitric oxide
- Hydrogen fluoride
While most of these metal fumes and gases are considered to be toxic, some have been classified as carcinogenic. These substances enter our body when we breathe along with the air we inhale and cause ill health. Individually, the high presence of Cadmium in welding fumes have been associated with cancer and kidney disease whereas Manganese affects the nervous and muscular system and can cause Parkinson’s disease.
Beyond a certain concentration, these substances can have a poisonous effect on the body and can even prove fatal. Poisoning is one of the serious hazards of exposure to welding fumes and the effects can range from minor complications for slight poisoning to life-threatening in cases of heavy exposure. High concentrations of carbon monoxide gas in the welding fume poses a risk of asphyxiation, respiratory paralysis or even cardiac arrest by cutting down the supply of oxygen to the blood.
Additionally, welding fumes expose workers to lead and lead poisoning which is known to cause brain damage and other neurological effects. Soluble barium compounds, fluorides and calcium oxide are some other toxic constituents found in welding fumes. It is worth noting that smokers are at a higher risk of being affected by the welding fume exposure than non-smokers, though non-smokers too face a significant risk.
Factors Affecting the Toxicity of the Fumes
The composition of the metal fumes and its toxicity vary depending on the metal being welded, type of welding technique and tool used, etc. For instance, the fume from welding stainless steel is more toxic due to the presence of chromium and nickel than the fume produced from welding mild steel. Similarly, manual metal arc (MMA) welding generates more toxic fumes than MIG welding as the former technique produces more of the toxic Hexavalent chromium. TIG welding is one of the welding techniques that produce the least fumes. Maximum fume production is generated in the Flux Core Arc Welding method.
Also, the coatings present in the welding metal are responsible for producing toxic fumes. Metal coatings, plastic coatings, primers that contain lead oxide, solvents, paints, rust inhibitors and even oil coatings produce harmful vapors and toxic fumes when welded. So, it is always advisable to remove the coatings from the metal before welding using stripping products or wet slurry vacuum.
The fumes are highly concentrated and most toxic at the source, that is when the smoke leaves the metal and as it dissipates mixing with the air the toxicity comes down significantly. The composition of the welding rod, filler metals, the location of the workstation and ventilation are some of the other factors that affect the worker’s exposure to welding fumes.
Can Exposure To Metal Fumes Cause Poisoning?
Yes, exposure to toxic particles and gases present in the welding fumes at high concentrations or prolonged exposure at low concentrations can cause poisoning. Heavy metal poisoning can be caused by consuming food contaminated with heavy metals or by breathing in air that contains airborne heavy metals. Toxic levels of metals like arsenic, cadmium, mercury and zinc in the welding fumes can cause heavy metal poisoning.
Types of Poisoning
Certainly, heavy metal poisoning can be classified into different types depending on the metal that causes the poisoning and the amount of exposure. The signs and symptoms may vary for each of these types of poisoning. Some of the types of poisoning caused by welding fumes are:
Acute poisoning can be caused by exposure to a heavy dose of metals at high concentrations. This type of poisoning is a medical emergency and requires immediate medical assistance. Acute poisoning typically displays immediate symptoms such as:
- Loss of consciousness
“Toxic drink” (CC BY-SA 2.0) by dmuth
This type of heavy metal poisoning is caused by prolonged exposure to low doses of metal fumes. To explain further, the metals slowly build up in the body’s soft tissues, and when it exceeds a threshold, it can result in poisoning and other serious complications. Chronic poisoning slowly develops symptoms like:
- Muscle and joint pain
Though lead poisoning also falls under heavy metal poisoning, the condition has its own set of characteristics and is one of the most common causes of poisoning caused by metals. Also, lead in the welding fumes can accumulate in the body over time due to prolonged exposure and develop complications. If you are exposed to very high levels of poisoning, lead poisoning can be fatal. It is usually characterized by symptoms like:
- Abdominal pain
- Sleeping disorders
- High blood pressure
- Pain in the muscles and joints
- Mood disorders
- Reduced sperm count
- Risk of miscarriage, stillbirth or premature in pregnant women
While it is usually adults who are at risk with lead in welding fumes, it is important to ensure there are no children around the welding work area. Above all, lead poisoning poses a more serious risk for children, especially under the age of 6. From developmental delays to weight loss, sluggishness, vomiting, hearing loss and even seizures, exposure to toxic levels of lead can cause a number of complications in children.
Poisoning caused by exposure to arsenic can also have its own set of symptoms like skin lesions, redness and swelling of the skin, unusual heartbeat, vomiting, and diarrhea.
How To Prevent Poisoning
Poisoning from metal fumes can simply be prevented by avoiding and reducing exposure to welding fumes. This can be done by ensuring the workspace adheres to the occupational safety regulations as required by the safety enforcement agencies. By taking these precautionary measures, we can protect ourselves from the risk of poisoning and other problems posed by the metal fumes and toxic gases that constitute welding fumes. These are some of the ways to prevent poisoning by reducing exposure to toxic metal fumes:
- Wear welding gear or Welding respirator to avoid inhaling the metal fumes and toxic gases
- Use ventilation and exhaust systems in the workstation to keep the toxic fumes out of the breathing zone
- Ensure exhaust ports are kept away from other workers
- Avoid crouching over the work area and keep a safe distance from the fumes
- When welding outdoor, position yourself upwind to avoid inhaling the fumes.
- Avoid welding in closed, confined spaces that do not have proper ventilation. Welding in enclosed spaces poses a risk of suffocation as welding fumes contain gases like helium, argon and carbon dioxide
- Using fume hoods, vacuum nozzles or fume extractors can help to remove most of the toxic fumes and gases at the source
- Use base or filler metals that generate less toxic fumes
- Using pure CO2 instead of argon blends for shielding gas
- Employing the welding process that generates the least amount and the least toxic fumes. MIG and TIG welding produces the least fumes in comparison
- Reducing the heat input to only as much as needed with spark control will minimize the fumes generated
- Before welding ensure the surface of the metal is free from coatings or residues like paint, solvents, etc., as these can be potentially toxic. Strip the coatings before the welding process
What To Do If Poisoned?
If you have been exposed to welding fumes and suspect you could be poisoned, seek medical assistance immediately. Depending on your symptoms, your doctor may conduct a blood or urine test. In some cases, an X-ray may also be required. Also, if the results confirm poisoning, doctors provide treatments typically ranging from pumping the stomach to draw the metals out to Chelation in cases of serious poisoning.
In the process of Chelation, patients are administered a pill or injection that binds the metals accumulated in the body and flushes it out of the body. Self-diagnosis and over the counter treatments should be avoided at all costs. In case of poisoning, slight or heavy, it is important to stay away from the welding fumes to avoid making it worse until the treatment is over and doctors deem you safe.
To help with the treatment, doctors may also advise changes in diet and lifestyle to reduce exposure to heavy metals as some foods and environmental factors can also cause Heavy metal poisoning. Things like high mercury fish and Lead-based paints should be avoided as these can further increase the risk of poisoning.
Whether you are a professional welder or a hobbyist practicing DIY welding on your projects, it is absolutely necessary to adhere to the welding safety regulations to protect yourself and those around you from the risk of poisoning.
Professional welders need to make sure their workspace is engineered to reduce exposure to fumes and has the necessary safety controls as required by their local safety and health enforcement agency. Investing in a quality welding respirator or fume extractor is necessary as professional welders are continuously exposed to welding fumes.
Hobbyists and other non-professionals need to fully understand the hazards associated with welding and its toxic fumes before venturing into it. In the absence of a workstation, it is important to choose the right workspace that will not expose you or others to the metal fumes and also has the necessary ventilation.
Most importantly, knowing you are safe from the hazards will let you work without apprehensions and develop your skill the way you want.