Sizes of airborne particle as dust, pollen bacteria, virus and many more

Particle Sizes
Sizes of airborne particle as dust, pollen bacteria, virus and many more
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The size of contaminants and particles are usually described in microns, a metric unit of measure where one micron is one-millionth of a meter. There are 25,400 microns in one inch. The eye can see particles to about 40 microns.

The size of some contaminants and particles are indicated in the table below.

Particle Particle Size
(microns)
one inch 25,400
dot (.) 615
Eye of a Needle 1,230
Glass Wool 1000
Spanish Moss Pollen 150 - 750
Beach Sand 100 - 10000
Mist 70 - 350
Fertilizer 10 - 1000
Pollens 10 - 1000
Cayenne Pepper 15 - 1000
Textile Fibers 10 - 1000
Fiberglass Insulation 1 - 1000
Grain Dusts 5 - 1000
Human Hair 40 - 300
Human Hair 60 - 600
Dust Mites 100 - 300
Saw Dust 30 - 600
Ground Limestone 10 - 1000
Tea Dust 8 - 300
Coffee 5 - 400
Bone Dust 3 - 300
Hair 5 - 200
Cement Dust 3 - 100
Ginger 25 - 40
Mold Spores 10 - 30
Starches 3 - 100
Red Blood Cells 5 - 10
Mold 3 - 12
Mustard 6 - 10
Antiperspirant 6 - 10
Textile Dust 6 - 20
Gelatin 5 - 90
Spider web 2 - 3
Spores 3 - 40
Combustion-related Carbon Monoxide from motor vehicles, wood burning,
open burning, industrial processes up to 2.5
Fly Ash 1 - 1000
Milled Flour, Milled Corn 1 - 100
Coal Dust 1 - 100
Iron Dust 4 - 20
Smoke from Synthetic Materials 1 - 50
Lead Dust 2
Face Powder 0.1 - 30
Talcum Dust 0.5 - 50
Asbestos 0.7 - 90
Calcium Zink Dust 0.7 - 20
Paint Pigments 0.1 - 5
Auto and Car Emission 1 - 150
Metallurgical Dust 0.1 - 1000
Metallurgical Fumes 0.1 - 1000
Clay 0.1 - 50
Humidifier 0.9 - 3
Copier Toner 0.5 - 15
Liquid Droplets 0.5 - 5
Insecticide Dusts 0.5 - 10
Anthrax 1 - 5
Yeast Cells 1 - 50
Carbon Black Dust 0.2 - 10
Atmospheric Dust 0.001 - 40
Smoldering or Flaming Cooking Oil 0.03 - 0.9
Corn Starch 0.1 - 0.8
Sea Salt 0.035 - 0.5
Bacteria 0.3 - 60
Bromine 0.1 - 0.7
Lead 0.1 - 0.7
Radioactive Fallout 0.1 - 10
Rosin Smoke 0.01 - 1
Combustion 0.01 - 0.1
Smoke from Natural Materials 0.01 - 0.1
Burning Wood 0.2 - 3
Coal Flue Gas 0.08 - 0.2
Oil Smoke 0.03 - 1
Tobacco Smoke 0.01 - 4
Viruses 0.005 - 0.3
Typical Atmospheric Dust 0.001 to 30
Sugars 0.0008 - 0.005
Pesticides & Herbicides 0.001
Carbon Dioxide 0.00065
Oxygen 0.0005

one micron is one-millionth of a meter
Airborne particles
Airborne particles are solids suspended in the air.

Larger particles - larger then 100 μm
terminal velocities > 0.5 m/s
fall out quickly
includes hail, snow, insect debris, room dust, soot aggregates, coarse sand, gravel, and sea spray
Medium-size particles - in the range 1 to 100 μm
sedimentation velocities greater than 0.2 m/s
settles out slowly
includes fine ice crystals, pollen, hair, large bacteria, windblown dust, fly ash, coal dust, silt, fine sand, and small dust
Small particles - less than 1 μm
falls slowly, take days to years to settle out of a quiet atmosphere. In a turbulent atmosphere they may never settle out
can be washed out by water or rain
includes viruses, small bacteria, metallurgical fumes, soot, oil smoke, tobacco smoke, clay, and fumes
Hazardous Dust Particles
Smaller dust particles can be hazardous for humans. In many jurisdictions dust fractions at specified particle sizes in working environments are required to be measured.

Inhalable Dust
Airborne particles which can enter the nose and mouth during normal breathing. Particles of 100 microns diameter or less.

Thoracic Dust
Particles that will pass through the nose and throat, reaching the lungs. Particles of 10 microns diameter and less. Referred to as PM10 in the USA.

Respirable Dust
Particles that will penetrate into the gas exchange region of the lungs. A hazardous particulate size less than 5 microns. Particle sizes of 2.5 micron (PM2.5) are often used in USA.