Aerosols Definition

by Laurent Cousineau
(Montreal)

Aerosols are small liquid or solid particles that are suspended in gas.

Depending on their composition, this dispersion of small particles can absorb or reflect sunlight in the atmosphere.

Examples of aerosols include paints, insecticides and detergents. These products are packaged under pressure and are released via a gaseous propellant.

Aerosols and Climate Change

Although there are natural aerosols which play a major role in the biosphere's water cycle, anthropogenic aerosols have an impact on the climate and our health that is still not fully understood.

In general, aerosols are quite complex in structure but they often contain sulfates, organic carbon, black carbon, nitrates, mineral dust, and sea salt.

About 90% of aerosols are natural and come from forest fires, which emit organic carbon, and volcanoes, which emit large quantities of ash into the atmosphere along with sulfur dioxide and other gases that contain sulfates.

Together, aerosols contribute to global warming slightly. The reason why they don't cause much warming is due to the fact that different types of aerosols have various different effects that will almost completely cancel each other.

In other words, some aerosols will actually have a cooling effect but the net effect of all anthropogenic aerosols will be the warming of the atmosphere.

Producers of Aerosols

Aerosols are also emitted via fossil fuel combustion and biomass burning.

As such, automobiles, incinerators, smelters, and power plants will emit aerosols in the form of sulfates, nitrates, black carbon, and other particles.

Moreover, deforestation, overgrazing, drought, and excessive irrigation will produce aerosols as well. In essence, as these alter the land surface, they increase the rate at which dust aerosols enter the atmosphere.

Even indoors, cigarettes, cooking stoves, fireplaces, and candles will emit aerosols.

Finally, although similar, aerosols should not be confused with particulate matter.

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