All scientists classify particulate matter by size. PM10 or coarse are particulate matter having the diameter between 2.5 micrometers and 10 micrometers. Its slightly bigger in size than PM2.5 but if we take human hair as reference, it is too small in size as human hair is between 50-70 micrometers thick. They can be seen with naked eyes. Smoke and dust are examples of PM10.
