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Indoor airborne particles can have an adverse effect on our health, and the smaller the particle the more invasive it can be. 

The particle size, rate of breathing, and whether your breathing through your mouth or nose all play a factor in how deep a particulate gets into your body.

While the human body has some natural defense mechanisms (coughing & sneezing) against airborne particles entering our lungs, the smaller particles can get past this defense.

So how small are these particles? Well typically only particles 40 microns and larger can be seen by the human eye.

While there are too many factors to predict just how far a certain size airborne particle can get into the human body, there are enough studies out there to give us a general idea.

  • Airborne particle sizes 25 to 100 microns can enter and settle in the nose and mouth.
  • Airborne particle sizes less than 25 microns can enter and settle in the head and lung airways.
  • Airborne particle sizes less than 10 microns can enter and settle deep into the lungs.
  • Airborne particle sizes less than 2.5 microns can enter the bloodstream from the lungs.

Here's a general guide to the sizes of different airborne particles:

Particle Particle Size (microns) 
Asbestos 0.7 - 90
Auto Emission 1 - 150
Bacteria 0.3 - 50
Beach Sand 100 - 10000
Carbon Black Dust 0.2 - 10
Cement Dust 3 - 100
Coal Dust 1 - 100
Copier Toner 0.5 - 15
Dust Mites 100 - 300
Fertilizer 10 - 1000
Fiberglass Insulation 1 - 1000
Grain Dusts 5 - 1000
Human Hair 40 - 300
Household Dust 0.5 - 100
Insecticide Dusts 0.5 - 10
Lead Dust 2
Milled Flour, Milled Corn 1 - 100
Mist 70 - 350
Mold Spores 10 - 30
Paint Pigments 0.1 - 5
Pollens 10 - 1000
Red Blood Cells 5 - 10
Saw Dust 30 - 600
Smoke from Synthetic Materials 1 - 50
Spores 3 - 40
Talcum Dust 0.5 - 50
Tobacco Smoke 0.01 - 4
Textile Dust 6 - 20
Viruses 0.005 - 0.3