Welding is the process of joining two or more pieces of metal together by melting a filler material to form a strong joint when the material has cooled; Thus, creating a reinforcing strength for structures, machinery, and countless applications. This process can also be used for plastic materials, but the term - welding - generally refers to metals.
However, the welding process is considered occupationally hazardous for many reasons, albeit some more than others; a major reason are the particles, fumes and smoke that create adverse side effects after inhalation. The major source of these particles is welding fume (or smoke).
Welding fume can be defined as a suspension of solid particles in a gas, and more specifically “fume” is used among aerosol scientists “to describe any airborne metal or metal oxide particles that condense from vapor.” This is precisely what happens when the metal is heated up rapidly during welding. Part of the metal is vaporized at the extreme temperature and then quickly cools and condenses into sub-micron particles in the airstream.
Another significant concentration of welding fume in the airstream comes from what is known as welding microspatter. These are liquid droplets that are small enough to remain airborne.
Welding fume hazards are a direct correlation of what can be inhaled through the welding process. Most of the hazardous substances are very fine, respirable particles of different types of metals, including:
Manganese containing fumes is one of the biggest risks encountered in welding smoke. Inhalation of the metal can cause serious damage to the brain and nervous system. Manganese fumes can result in the onset of Parkinson’s disease, a crippling disorder that affects movement and balance. It also causes “manganism,” which is closely related to Parkinson’s as it makes it difficult to move properly.
Iron oxide can also be contained in the welding fumes, which is very irritating to the respiratory system. There is also cadmium which is used to coat the metals, which can cause lung disease, emphysema, and kidney failure. Other harmful substances include lead oxides and asbestos.
Short-term health effects
Long-term health effects
Welding fume exposure can lead to a wide variety of negative health symptoms, which include, but are not limited to, harm or irritation to the lungs, heart, kidneys and nervous system. These health effects may be both short- and long term.
However, one of the most common health symptoms is Welding Fume Fever, also known as metal fume fever, brass founders’ ague, brass shakes, welding shivers, Monday morning fever, and/or the zinc shakes.
Metal fume fever is caused by inhaling certain metals during or after the process of welding, either as particulates or more commonly, fumes. Exposure of welding fumes typically form through the actual welding process, due to the heating of galvanized metals, alloys, and combustible compounds.
The signs of welding fume fever often relate to the flu, or resemble flu-like symptoms. Common ailments reported are having a fever, nausea, headaches (minor and severe), muscle aches, chest pain, and in some cases pneumonia (Flu-like symptoms normally disappear within 24 to 48 hours. Full recovery often requires one to three weeks). In the most severe cases of metal fume fever, patients reported a burning sensation in the body, lack of urine output, convulsive behaviour, high blood pressure, severe vomiting, and bloody diarrhea. If you or someone you know is experiencing these symptoms, please seek immediate medical attention or call 9-1-1 in case of an emergency.
Metal particles are not the only toxic substances that can result from welding. Often times the base metal is coated with paints or coatings. These coatings contain highly toxic chemicals that can be evaporated and inhaled. Other fumes and gases can come from fluxes in the electrode, from shielding gases, and from various cleansing agents and solvents. These all must be recognized and controlled for. Some of these gases are vapors and as such cannot be filtered by a particulate filter.
In “Particle Size Distribution of Gas Metal and Flux Cored Arc Welding Fumes” from the October 2005 edition of Welding Research, the authors discuss the concentration of submicron particles and their hazardous effect on human operators. They state that welding particles smaller than 20 microns can remain airborne. However, only those smaller than 1 micron are truly dangerous and can be deposited in the lungs as those greater “in size are trapped on the walls of the human airway before they reach the lungs. They are carried away in the mucus…” They further state that “only about 30% of particles (between 0.1 and 1 micron) eventually deposit in the lungs. Noting the inherent hazard of particle deposition in the lungs, the researches measured the size distribution of particles to find out the respirable fraction. They concluded that greater than 75% of all particles were less than 0.4 microns in size in MIG welding and greater than 90% of all particles were less than 0.7 microns in size. This differs from the 50% and 70% for flux cored arc welding. Clearly, most of the particles in the welding smoke are respirable.
Sentry Air Systems, Inc. provides this information as a customer service, but cannot be responsible for its accuracy or completeness. It is recommended that competent legal authorities as well as safety and hygiene professionals be consulted.