Understanding the Smell of Blood: What Causes the Metallic Odor?

The smell of blood is often described as metallic or coppery. This is due to the presence of iron in hemoglobin, the protein in red blood cells that carries oxygen. When blood is exposed to air, the iron in hemoglobin oxidizes and produces a characteristic odor. Other compounds that contribute to the smell of blood include carbon dioxide, ammonia, and lactic acid.