Aerosol: Definition & Examples

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

In this lesson, you're going to learn a bit about aerosols. First, we'll simply define what this is in general. Then, you'll learn about the specific sources of aerosols.

The Air Around You

Take a look at the air around you. If you live in a relatively clean place, you'll probably describe it with words like:

1. Clear

2. Clean

3. Odorless

Or something along those lines, of course. But despite the colorless and odorless nature of the air around you, it's anything but empty space. Though we cannot see them, there are gaseous atoms and molecules floating around. What are these? Let's find out on this lesson about aerosols.

What is an Aerosol?

Aerosol is a word that is used to describe a mixture of small liquid and/or solid particles dispersed in a gaseous system, such as air. The word aerosol comes to us from:

  • 'Aero-', which refers to gas in general or air specifically. Easy enough, right?
  • '-sol', which refers to a mixture of particulate matter in a fluid system (gas/air is a fluid).

The diameters of these small particles are roughly between 0.002 micrometers and 100 micrometers in size.

Ash particles (aerosols) as seen under an electron microscope.
Ash particles (aerosols) as seen under an electron microscope.



There are many such aerosols in our atmosphere. Let's go over some examples of naturally occurring ones first.

There are the primary atmospheric aerosols. These are aerosols that make it into our atmosphere directly from some sort of natural sources. For example, smoke and soot from wildfires, desert dust, and ocean waves whipping sea salt into the atmosphere.

There are also secondary atmospheric aerosols. These are aerosols that arise when gaseous substances are converted to particulate matter in the atmosphere. A great example of this is the sulfur dioxide gas emitted by a volcanic eruption. Once high up in Earth's atmosphere, the sulfur dioxide gas is actually converted to droplets of sulfuric acid.

About 90% of the aerosols are of natural origin.

Human Made

Of course, not all aerosols are natural. We, humans, create a lot of aerosols (about 10% of the total amount present on earth). These human-made aerosols are called anthropogenic aerosols, because the word anthropogenic means it is caused by ('-genic') humans ('anthropo-').

The aerosols arise as a result of:

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