Particulate Matter: Why monitor PM10 and PM2.5?
Thursday, July 21, 2022
Particulate air pollution is defined by the US EPA as an air-suspended mixture of both solid and liquid particles. They are often separated into three classifications; coarse, fine, and ultrafine particles. Coarse particles have a diameter of between 10 µm and 2.5 µm and settle relatively quickly whereas fine (1 to 2.5 µm in diameter) and ultrafine (<1 µm in diameter) particles remain in suspension for longer. Keep in mind that due to how the scale is built, PM10 (coarse) also automatically contains PM2.5 (fine) and PM1.0 (ultrafine). Additionally, PM2.5 (fine) contains PM1.0 (ultrafine) as well. To put things into perspective, human hair has a diameter of 50-70 µm and a grain of sand has a diameter of 90 µm.