City dirt has a great many different things in it. Among them, almost always, certain very small plants, far too small to be seen except with a pretty strong microscope. These are, in fact, a particular kind of bacteria. So we blow thru our skins, hole, dust, and bacteria. The hole heals over, but the bacteria stay inside.

City dirt has a great many different things in it. Among them, almost always, certain very small plants, far too small to be seen except with a pretty strong microscope. These are, in fact, a particular kind of bacteria. So we blow thru our skins, hole, dust, and bacteria. The hole heals over, but the bacteria stay inside.