smog


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Related to smog: photochemical smog, acid rain

smog

(smŏg) [smoke+fog], dense, visible air pollutionair pollution,
contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are transportation engines, power and heat generation, industrial processes, and the
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. Smog is commonly of two types. The gray smog of older industrial cities like London and New York derives from the massive combustion of coal and fuel oil in or near the city, releasing tons of ashes, soot, and sulfur compounds into the air. The brown smog characteristic of Los Angeles and Denver in the late 20th cent. is caused by automobiles. Nitric oxide from automobile exhaust combines with oxygen in the air to form the brown gas nitrogen dioxide. Also, when hydrocarbons and nitrous oxides from auto emissions are exposed to sunlight, a photochemical reaction takes place that results in the formation of ozone and other irritating compounds. In some instances, atmospheric pollutants accumulate and become concentrated when air movement is stopped by a temperature inversiontemperature inversion,
condition in which the temperature of the atmosphere increases with altitude in contrast to the normal decrease with altitude. When temperature inversion occurs, cold air underlies warmer air at higher altitudes.
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: Usually the air is warmer at the earth's surface and colder above; in a temperature inversion a layer of warm air forms above and holds down a layer of cool air at the ground. Smog usually results in reduced visibility, irritation of the eyes and respiratory system, and damage to paint, metal, rubber, and other materials. Prolonged smogs (generally caused by temperature inversions) are often lethal to persons with respiratory ailments. As the result of an unremitting smog in 1948 in Donora, Pa., more than 5,000 persons were reported ill and the deaths of 20 persons were recorded. In London, smog accounted for the deaths of more than 4,000 persons in 1952 and 106 persons in 1962.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Smog

 

the severe air pollution over large cities and industrial centers. There are two types of smog. One is a thick fog that contains smoke or gaseous industrial wastes as, for example, in London; the other is a pall of corrosive gases and aerosols in high concentrations (without fog). The latter type arises under the effect of ultraviolet solar radiation in the atmosphere as a result of photochemical reactions occurring in the exhausts of motor vehicles and the gaseous wastes of chemical plants as, for example, in Los Angeles. Smog is usually observed when there is low atmospheric turbulence and, consequently, an even distribution of air temperature with height, especially in temperature inversions during a calm or a slight wind.

Smog, which reduces visibility and accelerates the corrosion of metals and man-made structures, is also harmful to human health. Intense and prolonged smog can be a cause of increased morbidity and mortality.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

smog

[smäg]
(meteorology)
Air pollution consisting of smoke and fog.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

smog

A condition in which the surface visibility is reduced because of smoke particles suspended in the moist air.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

smog

a mixture of smoke, fog, and chemical fumes
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Astronauts and scientist manning the International Space Station (ISS) could even see the visible traces of the smoke and smog created by these slash-and-burn methods in space.
Biomass burning and mixed-type pollutants were found mostly originating from within Pakistan in the smog dominated zone, however, sources were also detected in neighbouring regions such as India, Afghanistan and Iran with Indian contributions mainly constituting to fine mode biomass/urban type pollutants.
Cities like Faisalabad, Sargodha, Lahore, Multan and Bahawalpur are majorly affected each year and thus smog is declared as a public health emergency in Pakistan also5.
She added experts have already shown their concerns over the impact of smog. She said that strict measures should be taken to protect the citizens from the repercussions of smog.
He said that smog was dangerous for health and the citizens should avoid stepping out unnecessarily, wash eyes their with fresh water, and gargle after returning home.
Punjab Environment Protection Department Director Naseem-ur-Rehman told APP that the modernised brick-kilns based on zig-zag technology would not only reduce the production cost of bricks and the fuel charges but also help control air pollution and smog.
'Special smog committees have been formed to monitor and control the sources of smog in the province,' he added.
A petitioner is the case shared that smog affects health and environment, adding that government should take precautions to prevent it.
This utter lack of trees led to the rise of smog in the provincial capital.
The decision was announced as different parts of the country, especially Punjab, have been facing prolonged blackouts triggered by dense smog.
Mixture of air pollutants in the environment is the basic cause of forming smog and can also be described as a mixture of numerous gases (burnt fumes and fuels from cars and industry) along with dust, sand, smoke, pollen and water vapors.2
A red alert for smog was issued Friday for Beijing and (http://qz.com/870001/beijing-lifts-its-red-alert-pollution-warning-after-a-week-of-red-alert-smog/) was finally lifted at midnight, but not before nearly a week of serious effects.