The toxic substance released when welding stainless steel is primarily hexavalent chromium (Cr(VI)). This substance is formed when chromium in the stainless steel oxidizes at the high temperatures involved in welding. Hexavalent chromium is highly toxic and carcinogenic, posing severe health risks, especially through inhalation. It can cause lung cancer, respiratory problems, skin dermatitis, and damage to internal organs. In addition to hexavalent chromium, nickel compounds are also released, which can cause allergic reactions and respiratory issues. Hexavalent chromium enters the body mainly by inhalation of the fumes released during welding. These fumes contain tiny particles that travel deep into the lungs and can cause long-term lung damage. Welding fumes from stainless steel also generate reactive oxygen species that contribute to cellular damage and inflammation in the lungs. In summary:

• The most hazardous toxic substance released is hexavalent chromium (Cr(VI)).
• Nickel compounds are also released and contribute to toxicity.
• Health risks include lung cancer, respiratory irritation, dermatitis, and systemic toxicity.
• Proper ventilation and protective equipment are essential to reduce exposure and health risks during stainless steel welding.