How big is an aerosol particle?
Aerosols cover a large range of sizes. Most aerosols range from 0.01 to 10 microns (µm) in aerodynamic diameter; the vast majority of atmospheric particulates are smaller than 1 micron in size. Particulate matter (PM) is often classified into three categories: particles with diameter greater than 2.5 and less than 10 microns (PM10, coarse particles), particles with diameter greater than 0.1 to less than 2.5 microns (PM2.5, fine particles), and particles with diameter less than 0.1 microns (UFP, ultra-fine particles). This categorization has physiological significance – PM10 particulates can be respired, PM2.5 can be absorbed by the lungs upon respiration, and UFP can enter the blood stream and be absorbed by organs such as the brain.
