Fume comprises particulate fume (which you can see) and gaseous fume which is not visible.
Welding and cutting
The amount of fume produced and its content depend on the steel, the consumables, fluxes and gases in addition to the process being used to weld or cut the steel.
- Particulate fume from mild and low carbon steels normally comprises iron oxide plus some manganese oxide and possibly barium from some self-shielded wires, inorganic fluorides and from basic MMA electrodes.
- Alloy steels also contain oxides of the alloying elements present.
- If gaseous fume is produced the most important component is ozone, a reactive, toxic, gas.
- The processes tending to give most fume are cored wires, MMA, and MIG welding, and plasma cutting. Those giving the least are TIG and submerged arc welding and gas cutting.
- At high currents the open arc processes MIG, TIG, and cored wire welding can generate ozone at high current when using argon-rich gases.
- Welding with CO2 gas does not produce ozone.
Fume production - hazards
Generally, as process current increases so does fume production.
- Particulate fume from welding and cutting steel is not thought to present any major hazards.
- Alloying constituents, manganese, nickel, and chromium only tend to be produced in low concentration.
- If ozone is generated then precautions must be taken to keep exposure to a minimum