Aerosol

Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are smoke, oceanic haze, air pollution, and smog. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can. The word aerosol derives from the fact that matter "floating" in air is a suspension (a mixture in which solid or liquid or combined solid-liquid particles are suspended in a fluid). To differentiate suspensions from true solutions, the term sol evolved—originally meant to cover dispersions of tiny (sub-microscopic) particles in a liquid. With studies of dispersions in air, the term aerosol evolved and now embraces both liquid droplets, solid particles, and combinations of these. An aerosol may come from sources as various as a volcano or an aerosol can.

Workplace exposure

Concentrated aerosols from substances such as silica, asbestos, and diesel particulate matter are sometimes found in the workplace and have been shown to result in a number of diseases including silicosis and black lung. [cite web
last =
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title = Aerosols
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publisher = United States National Institute for Occupational Safety and Health
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url = http://www.cdc.gov/niosh/topics/aerosols/default.html
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accessdate = 2008-03-15] Respirators can protect workers from harmful aerosol exposure. In the United States the National Institute for Occupational Safety and Health certifies respirators through the National Personal Protective Technology Laboratory to ensure that they protect workers and the public from harmful airborne contaminants. [cite web
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title = Respirators
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publisher = United States National Institute for Occupational Safety and Health
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url = http://www.cdc.gov/niosh/npptl/topics/respirators/
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accessdate = 2008-03-15]

Effect on climate

Anthropogenic aerosols, particularly sulfate aerosols from fossil fuel combustion, exert a cooling influence on the climate. [" [http://www.grida.no/climate/ipcc_tar/wg1/figspm-3.htm Climate Change 2001] "United Nations Environmental Program Intergovernmental Panel on Climate Change] The cooling effect of aerosols, however, does not seem to directly counteract the warming induced by greenhouse gases such as carbon dioxide, methane and water vapor and is accounted for in climate models, despite some claims that "global dimming" by aerosols may counteract global warming. [Citation
last = Romanou
first = Anastasia
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last2 = others
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title = 20th century changes in surface solar irradiance in simulations and observations
journal = Geophysical Research Letters
volume = 34
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pages = L05713
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year = 2007
url = http://pubs.giss.nasa.gov/docs/2007/2007_Romanou_etal.pdf
doi = 10.1029/2006GL028356
id = ]

Recent studies of the Sahel drought [ [http://apollo.eas.gatech.edu/EAS6792/presentations/aerosol_effects.ppt Pollutants and Their Effect on the Water and Radiation Budgets] ] and major increases since 1967 in rainfall over the Northern Territory, Kimberley, Pilbara and around the Nullarbor Plain have led some scientists to conclude that the aerosol haze over South and East Asia has been steadily shifting tropical rainfall in both hemispheres southward [ [http://www.csiro.au/files/files/pbg2.pdf Australian rainfall and Asian aerosols] ] . The latest studies of severe rainfall declines over southern Australia since 1997 [ [http://www.theage.com.au/news/national/pollution-rearranging-ocean-currents/2008/01/21/1200764169893.html Pollution rearranging ocean currents] ] have led climatologists there to consider the possibility that these Asian aerosols have shifted not only tropical but also midlatitude systems southward.

References

ee also

* Aerosol spray, the spraying device
* Bioaerosol
* Particulate, mixed-phase state of matter
* Pollution

External links

* [http://www.aaar.org American Association for Aerosol Research]