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



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