Aerosols: From Ash in the Wind to Smoke from the Stack

04.16.10 - When we hear the word "aerosol," most of us think of spray cans and perhaps the ozone hole. But spray cans are just a very small part of the story. Any airborne solid particle or liquid droplet -- whether it comes from a pressurized canister, the smokestack of a factory, or a dust storm -- is technically an aerosol.

Because of their diminutive size -- most individual aerosol particles are invisible to the human eye -- it is easy to overlook them. Yet collectively, they have a dramatic impact, affecting our health, our weather, our climate -- even the color of sunsets and the brightness of clouds. And, as we saw this week, they can even snarl air traffic and shut down airports.

Aerosols, or the gases that lead to their formation, come from vehicle tailpipes and desert sands, from sea spray and fires, volcanic eruptions and factories. Even lush forests, soils, or communities of plankton in the ocean can be sources of aerosols. These ubiquitous particles fall on our skin, layer the surfaces of our food, and linger in our air. No matter how much we scrub, vacuum, or clean, we'll never be able to seal ourselves off from them.

It's the small, fine and ultrafine aerosols that pose the greatest threat to our health. While larger particles (such as sea salt) tend to fall rapidly from the air, smaller ones remain aloft and can work their way into the lungs and bloodstream, fueling a variety of cardiovascular and respiratory diseases.