Fact Frenzy tackles the question: Is blood ever blue? This ageless question takes me back to my early days in elementary school, when I was first exposed to this argument among other classmates. I can recall the first time I’ve heard this preposterous statement — the contention among the misinformed that blood is blue until it is exposed to oxygen, air, atmosphere, etc.
Here come the facts! Blood is red, inside your body and out. That is, unless you’re a fictitious character such a Vulcan from Star Trek, then your blood may be green or some other color. But if you’re a human being from the planet earth, your blood and mine runs through our veins and arteries as red.
There are all sorts of discussions on this topic, believe it or not, with people in their adulthood still believing the myth that blood is ever blue, at any time, inside the human body. One of the causes of this myth comes from looking at your wrists (or other parts of your body where veins may be visible) — there are veins that appear blue. So of course, this must mean that the blood it carries is also blue, right?
Wrong.
The reason the veins appear blue has to do with the spectrum of light we see as we view the veins through skin. A phlebotomist wrote of an experiment using glass tubes of blood immersed in milk, in which they appeared blue at a certain depth. A more detailed explanation of the phenomenon of this type of “color change” is outside the scope of this article, but can be found at “The Straight Dope“.
Others have tried to claim that blood is blue only in some parts of the body where blood hasn’t been oxygenated. This is also false.
One must distinguish the difference between arteries and veins. Veins carry blood to the heart, and arteries carry blood away from the heart. The only small piece of accuracy to the myth in question is that oxygenated blood is a lighter red than in blood where the oxygen has been used up, which will be a darker red — far from being blue, or even purple as some might say. Therefore, you will see a difference depending on whether blood is drawn from arteries or veins — the latter being darker in color.
- Fact Frenzy
