Welding fumes are a mixture of metal fumes and gasses produced during welding operations. They generally have different compositions, depending on the metals used for welding, so they contain several contaminants.
- Mixture of airborne particles and gasses released or produced by the welding process
- Composition varies according to the welding process and typically contains metal oxides and other metal reaction products, particulate from flux of electrodes and gases produced by UV light like ozone and shielding gases
- Finer dust mass fraction is alveolic and can accumulate in the lungs and remain in the body
- Compounds. 90% of the particles come from the welding consumables
Welding fumes enter the human body through the lungs. They mix with the air we inhale.
The picture below illustrates the size of welding fume particles compared to other particles.
MAC (Maximum Allowable Concentration) is the common abbreviation for a legal exposure standard. It is defined as the allowable time-weighted average concentration for an 8-hour work day and a 40-hour work week in which a worker may be repeatedly exposed without adverse health effects. Related value in the USA is TLV (Threshold Limit Value), this is not a legal standard but a guideline published by the American Conference of Governmental Industrial Hygienist (ACGIH). Both values are measured in the breathing zone of the welder.
The concentrations are given in mg/m3 for various welding processes without using welding fume extraction systems.