Environmental problems you don't hear about...

Environmental problems you don't hear about...  One of these I discovered years ago, in reading a book about why cities are so dirty.  Once people stopped low temperature combustion (like wood fires, or coal fires) that made carbon soot in staggering quantities, why do cities still get dirty so quickly?  Especially noticeable is the black crud that accumulates on building walls.  What is that?  As you might guess, it's a complicated mess of stuff, but it's dominated by rubber dust – the tiny particles of rubber that wear off tires.  It turns out that is really nasty stuff, and it's been implicated in quite a few health issues that city dwellers suffer much more than rural folks.  There's a much higher concentration of rubber dust in cities.

This morning I read about another pollutant that in many ways reminds me of this: microscopic fibers shed by garments made with synthetic (plastic) fibers.  These are far larger fragments than rubber dust particles, but still small enough in many cases to affect individual cells.  It sounds like something we really should understand better than we currently do...