The Relative Size of Particles From the COVID-19 pandemic to the U.S. West Coast wildfires, some of the biggest threats now are also the most microscopic. A particle needs to be 10 microns (pm) or less before it can be inhaled into your respiratory tract. But just how small are these specks? Here's a look at the relative sizes of some familiar particles Human hair 50-180 µm Fine beach sand 90 µm Grain of salt 60 µm White blood cell 25 µm Grain of pollen 15 µm Dust particle < 10 µm Red blood cell 7-8 µm Respiratory droplets 5-10 µm Dust particle 2.5 µm Bacterium 1-3 µm Wildfire smoke 0.4-0.7 µm Coronavirus 0.1-0.5 µm T4 bacteriophage 225 nm Zika virus 45 nm #Particles #Relative #Size #Particles #virus #bacteria #pollen #comparison #droplets
