What is a Micron?

A micron is a unit of measure in the metric system. It equals one-millionth of a meter and one-thousandth of a millimeter. It is a shorten word for micrometer.

Micrometers measure things that are very small. It is ideal for measuring things that are so small that the naked eye can barely see it. And it is ideal for measuring things so small that that the naked eye cannot see it. For example, airborne allergens such as pollen and mold spores usually fall just below the level of what the eye can see.

The word comes from the Greek word "Mikros" which means small.

The table below shows the placement of this unit of measure in the metric system.

You can see how small of a unit of measure that it is. If you were using a high power microscope or a SEM microscope and wanted to measure what you were looking at, the next unit of measure that is smaller is a nanometer. One thousand nanometers equals one micron.

How to Visualize such a Small Unit of Measure

I will try to describe a visual picture to put such a small size into perspective. To know that 25,400 microns equals one inch is one thing. To understand and to be able to visualize what that means is another.

To begin, I want to establish a point of reference that we can all relate to. Copy paper for the computer printer can vary in thickness. For this example, we will say that the average thickness of common copy paper is 100 microns. I arrive at this figure by measuring a ream of 500 sheets of paper. I take that measurement and divide by 500 and come up with a figure that is very close to .12 mm.

Pick up a piece of paper and look at the edge (the thickness) and you will see that the period at the end of this sentence is bigger.

The horizontal line at top of the picture represents the top of the paper which is the writing side. The bottom line in the picture represents the bottom of the paper which would be the side that is touching the desk as you write.

Look at the edge thickness of a piece of paper and then look at the diagram above. This should help this small size into perspective.

If a piece of paper was lying flat on your desk, the right side of the picture above shows what a hundred microns would look like stacking upon top of each other along the edge (the thickness) of the paper.

This unit of measure makes it the ideal unit of measure for airborne allergens. As shown in the article Particle Sizes of Airborne Allergens, most allergic airborne triggers range between 1-100 microns in size. And when talking about nasal allergies, the smaller the particle size, the more potential it has to stay airborne longer before settling. This results in more of a chance for the allergens to be breathed in.

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