PM1- Ultrafine particles with an aerodynamic diameter less than 0.1 micrometers. Ultra-fine dust is the most damaging variant of fine particles.
PM2.5 - refers to particles that have a diameter of less than 2.5 micrometers (more than 100 times thinner than a human hair) and remain suspended for longer. These particles include viruses & bacterias as well as fine dust particles that are formed as a result of burning fuel and chemical reactions that take place in the atmosphere.
PM10 - is particulate matter 10 micrometers or less in diameter such as larger dust particles, pollen, and smoke.