45 Myths and Old Wives Tales People Still Believe Even Though They Have Been Debunked Long Ago

There’s an urban legend that says our blood is blue until it comes into contact with oxygen. In reality, human blood is never truly blue; it is always some shade of red. This myth likely originated from the observation that veins, which carry blood back to the heart, often appear bluish or greenish through the skin.

However, this is simply a result of the way our skin and subcutaneous tissue scatter and absorb light, making veins appear differently colored. Our blood is rich in oxygen, which gives it a bright red hue when it is oxygenated and a darker red when it is deoxygenated.