On the downside I've started paying attention to a strange black dust that appears by my windows. It's been appearing by my work windows for some time, and I'd like to know what it is. Top theories so far have been rubber, brake-pad materials, and diesel exhaust. Though I should collect some and see if I can get someone at caltech to tell me what it is.
I also found a paper in March 6th issue of The Journal of the American Medical Association called Lung Cancer, Cardiopulmonary Mortality, and Long-term exposure to Fine Particulate Air Pollution.
Their conclusion was that living in a polluted metropolitan area was about as dangerous as being overweight/obese. (Though not as bad as their worst category of obsesity)