Background Information on Particulate Matter
Particulate matter consists of small particles suspended in the atmosphere. Dust, pollen, sea salt, soil particles, mold, soot, smoke, and other fine substances create a mixture of particulate matter that we inhale with every breath. According to the EPA, particulate matter greater than 10 micrometers is generally filtered away in our nose and throat. Particulates less than 10 micrometers can often pass into the lungs.