Generations of children left school believing blood is blue until it touches oxygen, when it turns red. But that’s totally wrong. Blood is always red. Veins appear blue only because of how light is filtered as it penetrates the skin.
Generations of children left school believing blood is blue until it touches oxygen, when it turns red. But that’s totally wrong. Blood is always red. Veins appear blue only because of how light is filtered as it penetrates the skin.