Understand Airborne Particles

Larger particles – larger than 100 μm

• terminal velocities > 0.5 m/s
• fall out quickly
• includes textile fibers, dust mites, room dust, soot aggregates, sand, gravel etc

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Medium-size particles – in the range 1 to 100 μm

• sedimentation velocities greater than 0.2 m/s
• settles out slowly
• includes pollen, hair, large bacteria, plant spores, mold spores, mold, haze particles

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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, soot, tobacco smoke etc.

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Hazardous Dust Particles

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Inhalable Dust ≤ 100 microns

Airborne particles smaller than 100 microns can be inhaled into the mouth or nose through normal breathing but will not enter the lungs. Which is very common along the roads or in a dusty environment. Wearing a regular mask solves this issue.

Thoracic Dust (PM10) ≤ 10 microns

Airborne particles which are 10 microns or smaller will be able to pass through the nose and throat and eventually reaching the lungs. Particles such as mold and its spores fall into this category.

Respirable Dust (PM2.5) ≤ 2.5 microns

Airborne particles in this region is the biggest concern with governments’ worldwide. As they will be able to penetrate into the lungs and eventually in to the blood stream.

Sub microscopic Particles (PM0.3) ≤ 0.3 microns

Small Bacteria, Virus and tobacco smoke fall into this category they are so small in size mechanical filters are pushed to their limits to trap these fine particles, they are mostly airborne and can spread very easily and quickly.