Aerosol

Aerosol

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Aerosol

Aerosol-contamination in northeastern India and Bangladesh.

Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are smoke, oceanic haze, air pollution, smog and CS gas. 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
Effect on climate
References
See also
External links

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.^[1] 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.^[2]

Effect on climate

Anthropogenic aerosols, particularly sulfate aerosols from fossil fuel combustion, exert a cooling influence on the climate.^[3] 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.^[4]

Recent studies of the Sahel drought^[5] 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^[6]. The latest studies of severe rainfall declines over southern Australia since 1997^[7] have led climatologists there to consider the possibility that these Asian aerosols have shifted not only tropical but also midlatitude systems southward.

Oxides of nitrogen (NO_x) in the atmosphere are a form of pollution which can give rise to smog and act as a greenhouse gas. Their persistence in the atmosphere is affected by aerosol droplets of water. In 1964 long chain fatty acids, either naturally produced from marine organisms dispersed into the atmosphere by wave action or man-made, were found to coat these droplets. In 2006 there was a study of the effect of the LCFA on the persistence of NO_x, but the the long term implications, although thought to be significant, have yet to be determined.^[8]