|Airborne particulate size chart|
Logarithmic scale shows particle diameter in microns
The article talks about PM2.5, which it refers to as particles less than 2.5 mm in diameter. In my book 'mm' means millimeters. 2.5 mm would be a tenth of an inch in diameter. That doesn't seem right. I suppose the author thought that mm was a suitable abbreviation for micrometers. Hence my preference for the term 'microns'.
Note that the scale is logrithmic and goes from 1,000 microns (which is 1 millimeter) on the right down to one-ten-thousandth of a micron (or 1 angstrom) on the left. One millimeter is about the thickness of a dime. One angstrom is about the diameter of a water molecule, hence the 'Gaseous Contaminates' cloud in the lower left corner.
One commentor noted that ". . . none of China's worst polluted cities is even in the world top ten", which leads us to:
|World's most polluted city|