Selecting Proper Welding Processes to Reduce Fume Exposure

When selecting the proper welding process for the task, evaluating the potential for fume generation and the availability of different, lower-fume welding processes may help lower your exposure to harmful compounds in welding fumes.

Description:

There are a variety of different welding processes that can be used to join two pieces of metal.  Some of the most common types are shielded metal arc welding, gas metal arc welding, flux cored arc welding, and gas tungsten arc welding.  The sources of harmful welding fumes are mainly the "consumables," such as electrodes, rods, and filler metals, as well as the base metal and coatings.  However, the type of welding process can also have an influence.
 
Each welding process has advantages and disadvantages for different types of work. However, some types of welding consistently produce higher levels of harmful fumes than others.  Generally, the rate of fume generation for each welding process is as follows:  
 
 
 
 
 
Shielded Metal Arc Welding (SMAW), also known as stick welding, is commonly used to weld iron and steel.  This method of welding has been around for a long time, and is inexpensive to set up.  However, the weld is usually less aesthetically pleasing and the rate of fume generation is high.   
 
Source: United States Army
 
 
 
Gas Metal Arc Welding (GMAW), also known as Metal Inert Gas (MIG) welding, is commonly used in industrial settings on many different types of metals.  It is easy to learn, although it can be affected by environmental factors like rain or wind.  The four subtypes of GMAW include spray, pulsed-spray, globular, and short-circuiting.  Pulsed-spray usually generates the lowest amount of fumes.
 
Source: Thefabricator.com
 
 
 
Flux Cored Arc Welding (FCAW) is fast, inexpensive, portable, and common in construction settings.  It is usually used to weld steel or stainless steel.
 
Source: Lincolnelectric.com
 
 
 
Gas Tungsten Arc Welding (GTAW), also known as Tungsten Inert Gas (TIG) welding, is commonly used to weld stainless steel or non-ferrous metal.  It can be more time-consuming because the consumable is separate from the electrode.  It typically generates much lower concentrations of fumes, and can create a very precise weld. 
 
Source: Wballoys.co.uk

Risks Addressed:

Exposure to welding fumes can cause a variety of health problems.  One of the most well-known is “metal fume fever,” which is characterized by tiredness, fever, nausea, aches, and chills.  However, welding fumes are made up of many different components depending on the base metal, the consumable, the shielding gas, and the welding process.  There are many other serious health problems that can affect welders depending on what compounds are in the fumes that they inhale.  Some of the most toxic compounds commonly found in welding fumes are:
 
  • Manganese is a metallic element that is present in most welding fume samples.  Although a very small amount is required for normal bodily function, excessive exposure can cause serious health problems.  Welders exposed over long periods of time can show symptoms of manganism (also called “parkinsonism”), a degenerative brain disease that causes tremors, impaired speech and movement, muscle spasms, mood disturbances and hallucinations.  The American Conference of Governmental Industrial Hygienists’ (ACGIH) Threshold Limit Value (TLV) for manganese is .02 mg/m3. 
  • Hexavalent chromium is usually found in fumes when welding, cutting, or burning stainless steel, high chrome galvanized steel, and other chrome-containing metals.  It can cause skin, throat, nose, and lung irritation and sores.  It is also very strongly associated with lung cancer and other cancers of the throat or nasal passages.  The National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) for hexavalent chromium is 0.2 ug/m3.  However, it’s important to remember that there is no safe level of a cancer-causing substance.
  • Lead can also be present in welding fumes if the base metal has a lead-containing paint or coating.  Exposure to lead can cause a wide variety of health effects in almost every part of the body, but the most disturbing effects are neurological, affecting the brain, spine, and nerves.  They include memory loss, headache, irritability, cognitive dysfunction, and brain damage.  Kidney damage, joint pain, digestive issues, miscarriage, and infertility can also result.  The Occupational Safety and Health Administration’s (OSHA) Permissible Exposure Limit (PEL) for lead is 50 ug/m3.
  • There are many other harmful substances in welding fumes, including nickel, zinc, cadmium, beryllium, and others.  Each one has the potential to cause significant health issues.  In addition to the specific diseases mentioned above, exposure to any of these substances can also cause allergic sensitization.  Once you are sensitized, the only way to prevent an allergic reaction is by avoiding the substance.  Although some people can be exposed to a chemical hundreds of times without a reaction, other people may be sensitized the first time they are exposed. There is currently no way to predict who will become sensitized or when.

How Risks are Reduced:

Selecting a welding process that generates less fumes, along with taking other precautions such as ventilation at the point of operation and respiratory protection, decreases the likelihood that you will develop an illness associated with exposure to welding fumes.

Although some types of work require specific welding processes, you can often substitute one type of welding for another.  If you are using a process that generates a large amount of fumes like Shielded Metal Arc Welding, other types of welding like Metal Inert Gas Welding (MIG) or Flux-cored Arc Welding (FCAW) can often be substituted without sacrificing the quality of the work.

Effects on Productivity:

Although SMAW (or “stick” welding) has low initial costs, it may end up being more expensive per weld when all relevant factors are considered.  Stick welders must frequently make multiple passes on the same weld, and will need to take the time to chip or grind the slag left behind.  Especially when factoring in healthcare costs due to stick welding’s high fume generation rate, using an alternative welding process is likely to save time, labor, and money.

Additional Considerations:

Exposure to welding fumes and their components depends on many factors besides the type of welding process.  These factors include the type of flux (Pires, Quintino, Miranda & Gomes, 2007; Keane et al 2009), the voltage being used (Antonini et al, 2011), the consumable, and many others.  The individual components of welding fumes do not necessarily decrease proportionally with the total fume concentration.  Even if the concentration of total particulate is low, the concentration of other compounds may not be at safe levels. 
 
Regardless of which welding process you choose, it is extremely important to use engineering controls like local exhaust ventilation to control worker exposure to fumes.  If engineering controls do not lower the concentration of fumes and contaminants to acceptable levels, respiratory protection must be used.  The only way to determine if workers are overexposed is to perform personal air monitoring.  When collecting samples for personal air monitoring, it is important to consider other factors that may change from sample to sample to ensure valid results and OSHA compliance.  These include air movement, percent chrome in the base metal, consumable (wire, rods, flux, etc.) content, actual time welding, and the position of the head in relation to the welding plume. 

Contributors:

Sara Brooks, MPH, CPH - CPWR - The Center for Construction Research and Training

Mike McCullion, CSP, ARM - SMACNA - Sheet Metal and Air Condition Contractors' National Association

Mark Van Avery, Welding Assessor/CWI - International Training Institute

Availability

Controlling Hazardous Fume and Gases during Welding
To obtain information, visit Occupational Safety and Health Administration (OSHA)

Welding - Fumes and Gases
To obtain information, visit Canadian Centre for Occupational Health and Safety (CCOHS)

A Total Systems Approach to Controlling Welding Fumes
To obtain information, visit Lincoln Electric

Welding Fume and Gas Exposure
To obtain information, visit Occupational Health and Safety Online

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