# Am I breathing molecules from all before me?

1. Sep 19, 2012

### distar97

When a person breaths air, how many molecules were used in some form by people today and those before us?

The question becomes complex if you consider carbon dioxide is known to be drawn in by plants, trees and such. But could the question be simplified by asking how long does it take for a given liter of air to diffuse to every other liter of air in the atmosphere.

2. Sep 19, 2012

### JesseC

3. Sep 19, 2012

### distar97

Re: Am I breathing molecules from all before me?

I agree, comparing atoms makes more sense. I read the Marquette article. I tend to agree with Jeffrey Scott Nutall's reply that suggest that atoms used by a particular person are very likely to be used by any other person. If you consider how many atoms are in each liter of a person's breath and compare that to the number of liters of air available, I tend to believe the number of atoms can easily populate every liter of air given time to diffuse.

If this is true, the next question is how long does it take to get at least one atom from a liter of exhaled air to every liter in the atmosphere. We know that you can smell a drop of something like ethyl mercaptan across a room even if the room air seemingly not in motion. It may be faster than one would think.

I'm sure some here have looked at this in terms of environmental studies.

4. Sep 21, 2012

### SW VandeCarr

The atmosphere consists mostly of molecular nitrogen, $N_{2}$, and molecular oxygen, $O_{2}$ with smaller amounts of carbon dioxide and water vapor. There are no significant numbers of free inert atoms in the atmosphere. However, if you are tracing a particular atom over time, it may have had more than one molecular "home" since it arrived on the proto-earth (or rarely on the fully formed earth), due to chemical interactions. However intact atoms are nearly always found bound in molecules except for the very rare inert gases such as argon, neon and xenon.

Last edited: Sep 21, 2012
5. Sep 21, 2012

### Jimmy Snyder

Yuck. I just breathed an atom of oxygen that was breathed by Florence Foster Jenkins.

6. Sep 21, 2012

### SW VandeCarr

No. You breathed a molecule of oxygen that was breathed by FFJ, or you breathed an oxygen molecule, half of which was breathed by FFJ.

7. Sep 21, 2012

### edward

Naw you just recycled it. Sort of like a long flight on an older plane that recirculates the air.

8. Sep 22, 2012

### distar97

While interesting and certainly true, I'm ignoring whether it's a molecule or atom. A molecule
with at least one atom previously breathed would qualify.

I found something that goes into detail about my question nicely, and with lots of numbers.
http://www.vendian.org/envelope/dir2/breath.html

It appears everyone reading this post is breathing a few of my atoms right now.

I guess they're not really "mine" though.

DennisH

9. Sep 22, 2012

### Ken Natton

You should worry. I just breathed a molecule of methane that came out of a cow's rectum.

10. Sep 22, 2012

### leroyjenkens

And it probably had a bunch of bacteria on it. I hope you don't get sick.

11. Sep 22, 2012

### SHISHKABOB

the craziest thing is that we're all Ships of Theseus in a way

at least our skin is, definitely

12. Sep 22, 2012

### SW VandeCarr

A bunch of bacteria on a molecule? Surely you're joking (as was said to Dr. Feynman, who wasn't).

Last edited: Sep 22, 2012