smog
Top
(smŏg, smôg) 
n.
smogless smog'less adj.
n.
- Fog that has become mixed and polluted with smoke.
- A form of air pollution produced by the photochemical reaction of sunlight with hydrocarbons and nitrogen oxides that have been released into the atmosphere, especially by automotive emissions.
smogless smog'less adj.
WORD HISTORY New phenomena require new words, so it is not surprising that smog is a relatively recent coinage. The word followed the phenomenon by perhaps half a century, for air pollution was first noticed during the Industrial Revolution. The word smog is first recorded in 1905 in a newspaper report of a meeting of the Public Health Congress. Dr. H.A. des Vœux gave a paper entitled "Fog and Smoke," in which, in the words of the Daily Graphic of July 26, "he said it required no science to see that there was something produced in great cities which was not found in the country, and that was smoky fog, or what was known as 'smog.'" The next day the Globe remarked that "Dr. des Vœux did a public service in coining a new word for the London fog."
Top
Top
Polluted air over a community. The term, a combination of smoke and fog, was popularized in the early 20th century and now commonly refers to the pall of automotive or industrial origin that lies over many cities. Sulfurous smog results from the use of sulfur-bearing fossil fuels, particularly coal, and is aggravated by dampness. Photochemical smog requires neither smoke nor fog. Nitrogen oxides and hydrocarbon vapours emitted from automobiles and other sources undergo reactions in the presence of sunlight that produce a light brownish coloration of the atmosphere, reduced visibility, plant damage, irritation of the eyes, and respiratory distress.
For more information on smog, visit Britannica.com.
The noxious mixture of gases and particles commonly associated with air pollution in urban areas. Harold Antoine des Voeux is credited with coining the term in 1905 to describe the air pollution in British towns. See also Air pollution.
The constituents of smog affect the human cardio-respiratory system and pose a health threat. Individuals exposed to smog can experience acute symptoms ranging from eye irritation and shortness of breath to serious asthmatic attacks. Under extreme conditions, smog can cause mortality, especially in the case of the infirm and elderly. Smog can also harm vegetation and likely leads to significant losses in the yields from forests and agricultural crops in affected areas.
The only characteristic of smog that is readily apparent to the unaided observer is the low visibility or haziness that it produces, due to tiny particles suspended within the smog. Observation of the more insidious properties of smog—the concentrations of toxic constituents—requires sensitive analytical instrumentation. Technological advances in these types of instruments, along with the advent of high-speed computers to simulate smog formation, have led to an increasing understanding of smog and its causes.
Smog is an episodic phenomenon because specific meteorological conditions are required for it to accumulate near the ground. These conditions include calm or stagnant winds which limit the horizontal transport of the pollutants from their sources, and a temperature inversion which prevents vertical mixing of the pollutants from the boundary layer into the free troposphere. See also Meteorology; Stratosphere; Troposphere.
Smog can be classified into three types: London smog, photochemical smog, and smog from biomass burning.
London smog arises from the by-products of coal burning. These by-products include soot particles and sulfur oxides. During cool damp periods (often in the winter), the soot and sulfur oxides can combine with fog droplets to form a dark acidic fog. As nations switch from coal to cleaner-burning fossil fuels such as oil and gas as well as alternate energy sources such as hydroelectric and nuclear, London smogs cease. See also Acid rain; Coal.
Photochemical smog is a more of a haze than a fog and is produced by chemical reactions in the atmosphere that are triggered by sunlight. A. J. Hagen-Smit first unraveled the chemical mechanism that produces photochemical smog. He irradiated mixtures of volatile organic compounds (VOC) and nitrogen oxides (NOx) in a reaction chamber. After a few hours, Hagen-Smit observed the appearance of cracks in rubber bands stretched across the chamber. Knowing that ozone (O3) can harden and crack rubber, Hagen-Smit correctly reasoned that photochemical smog was caused by photochemical reactions involving VOC and NOx, and that one of the major oxidants produced in this smog was O3. See also Atmospheric chemistry; Ozone; Photochemistry.
While generally not as dangerous as London smog, photochemical smog contains a number of noxious constituents. Ozone, a strong oxidant that can react with living tissue, is one of these noxious compounds. Another is peroxyacetyl nitrate (PAN), an eye irritant that is produced by reactions between NO2 and the breakdown products of carbonyls. Particulate matter having diameters of about 10 micrometers or less are of concern because they can penetrate into the human respiratory tract during breathing and have been implicated in a variety of respiratory ailments.
Probably the oldest type of smog known to humankind is produced from the burning of biomass or wood. It combines aspects of both London smog and photochemical smog since the burning of biomass can produce copious quantities of smoke as well as VOC and NOx.
Top
"Smog" is a popular term used to describe polluted air. It was originally used as an abbreviation of the combination of coal smoke and fog that, along with sulfur dioxide vapor, characterized polluted air in London and other British cities in the 1950s. The term came into more widespread use as a summary description for the quite different pollution mixture of ozone (O3) and other photochemical oxidants (e.g., hydrogen peroxide, hydroxgl radical peroxy acetylnitrate) that characterized the air pollution in Southern California beginning in the 1950s, and in many other urban areas in the United States in the decades that followed. In the United Kingdom, the smog was black and acidic, while the smog in California was lighter in color and more highly oxidizing.
The black smoke in Britain was heavier in the winter months, and was most closely associated with its reducing power as a chemical (i.e., antioxidant), and with excess mortality, from chronic bronchitis and respiratory symptoms. By contrast, the California mixture was worse in the summer, and was characterized in terms of its oxidizing power. It attacked rubber and chemical polymers, and was associated with eye irritation, reduced lung function, and impaired athletic performance. In both mixtures there were fine particles that caused light to scatter and reduced the range of visibility.
In the United States, United Kingdom, and other economically developed countries in the twentieth century, the black smoke components of past pollution have largely been controlled, and the residual pollution problem is most closely related to the concentrations of light-scattering fine particles and ozone that form in the atmosphere from gaseous precursors (ie, pollutant chemicals whose reaction products have low vapor pressures and condense into fine particles). Such pollution mixtures are generally referred to as smog. While generally present at lower concentrations than in the past, these mixtures are still associated with excess cardiopulmonary mortality, morbidity, and physiologic function deficits. Attribution of the effects to specific components of the pollution mixture remains controversial, and further chemical characterization and health-effects research is now underway to resolve the remaining uncertainties.
(SEE ALSO: Airborne Particles; Air Quality Index; Ambient Air Quality [Air Pollution]; Automotive Emissions; Carbon Monoxide; Clean Air Act; Environmental Determinants of Health; Fossil Fuels; Fuel Additives; Inhalable Particles [Sulfates])
— MORTON LIPPMANN
Top
A combination of smoke and fog. The fog occurs naturally; the ‘smoke’ is introduced into the atmosphere by the activities of man. After the five-day-long period of smog in London in 1952, smoke abatement measures were introduced in Britain. British cities are still estimated to lose between 20 and 55% of incoming solar radiation from November to March through smog.
Furthermore, chain reactions occur in association with exhaust gases, notably in areas of intense car use such as Los Angeles. Toxic gases are formed. See also photochemical smog.
Top
smog (smŏg) [smoke+fog], dense, visible air pollution. 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 inversion: 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.
A haze or fog composed of water vapor, complex molecules, and suspended particles.
Top
A condition in which the surface visibility is reduced because of smoke particles suspended in the moist air.
Random House Word Menu:
Top
categories related to 'smoggy'
Top
For other uses, see Smog (disambiguation).
Smog is a type of air pollution; the word "smog" was coined in the early 20th century as a portmanteau of the words smoke and fog to refer to smoky fog.[1] The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London from the 19th century to the mid 20th century. This kind of smog is caused by the burning of large amounts of coal within a city; this smog contains soot particulates from smoke, sulfur dioxide and other components. Modern smog, as found for example in Los Angeles, is a type of air pollution derived from vehicular emission from internal combustion engines and industrial fumes that react in the atmosphere with sunlight to form secondary pollutants that also combine with the primary emissions to form photochemical smog.
|
Contents
|
Origin of term
Coinage of the term "smog" is generally attributed to Dr. Henry Antoine Des Voeux in his 1905 paper, "Fog and Smoke" for a meeting of the Public Health Congress. The July 26, 1905 edition of the London newspaper Daily Graphic quoted Des Voeux, "He said it required no science to see that there was something produced in great cities which was not found in the country, and that was smoky fog, or what was known as 'smog.'"[2] The following day the newspaper stated that "Dr. Des Voeux did a public service in coining a new word for the London fog." "Smog" also appears in a January 19, 1893, Los Angeles Times article and is attributed to "a witty English writer."
Photochemical smog
Photochemical smog was first described in the 1950s. It is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.[3] This noxious mixture of air pollutants can include the following:
- Aldehydes
- Nitrogen oxides, such as nitrogen dioxide
- Peroxyacyl nitrates
- Tropospheric ozone
- Volatile organic compounds
All of these chemicals are usually highly reactive and oxidizing. Photochemical smog is therefore considered to be a problem of modern industrialization. It is present in all modern cities, but it is more common in cities with sunny, warm, dry climates and a large number of motor vehicles.[4] Because it travels with the wind, it can affect sparsely populated areas as well.
Health effects
Smog is a serious problem in many cities and continues to harm human health.[5] Ground-level ozone, sulfur dioxide, nitrogen dioxide and carbon monoxide are especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma.[6] It can inflame breathing passages, decrease the lungs' working capacity, cause shortness of breath, pain when inhaling deeply, wheezing, and coughing. It can cause eye and nose irritation and it dries out the protective membranes of the nose and throat and interferes with the body's ability to fight infection, increasing susceptibility to illness. Hospital admissions and respiratory deaths often increase during periods when ozone levels are high.[7]
The U.S. EPA has developed an Air Quality Index to help explain air pollution levels to the general public. 8 hour average ozone concentrations of 85 to 104 ppbv are described as "Unhealthy for Sensitive Groups", 105 ppbv to 124 ppbv as "unhealthy" and 125 ppb to 404 ppb as "very unhealthy".[8] The "very unhealthy" range for some other pollutants are: 355 μg m−3 - 424 μg m−3 for PM10; 15.5 ppm - 30.4ppm for CO and 0.65 ppm - 1.24 ppm for NO2.[9]
The Ontario Medical Association announced that smog is responsible for an estimated 9,500 premature deaths in the province each year.[10]
A 20-year American Cancer Society study found that cumulative exposure also increases the likelihood of premature death from a respiratory disease, implying the 8-hour standard may be insufficient.[11]
Areas affected
Smog can form in almost any climate where industries or cities release large amounts of air pollution, such as smoke or gases. However, it is worse during periods of warmer, sunnier weather when the upper air is warm enough to inhibit vertical circulation. It is especially prevalent in geologic basins encircled by hills or mountains. It often stays for an extended period of time over densely populated cities or urban areas, and can build up to dangerous levels.
London
In 1306, concerns over air pollution were sufficient for Edward I to (briefly) ban coal fires in London.[12] In 1661, John Evelyn's Fumifugium suggested burning fragrant wood instead of mineral coal, which he believed would reduce coughing. The Ballad of Gresham College the same year describes how the smoke "does our lungs and spirits choke, Our hanging spoil, and rust our iron."
Severe episodes of smog continued in the 19th and 20th centuries, mainly in the winter, and were nicknamed "pea-soupers". The Great Smog of 1952 darkened the streets of London and killed approximately 4,000 people in the short time of 4 days (a further 8,000[13] died from its effects in the following weeks and months). Initially a flu epidemic was blamed for the loss of life.
In 1956 the Clean Air Act started legally enforcing smokeless zones in the capital. There were areas where no soft coal was allowed to be burned in homes or in businesses, only coke, which produces no smoke. Because of the smokeless zones, reduced levels of sooty particulates made the intense and persistent London smog a thing of the past.
It was after this that the great clean-up of London began. One by one, historical buildings which, during the previous two centuries had gradually completely blackened externally, had their stone facades cleaned and restored to their original appearance. Victorian buildings whose appearance changed dramatically after cleaning included the British Museum of Natural History. A more recent example was the Palace of Westminster, which was cleaned in the 1980s. Smog caused by traffic pollution, however, does still occur in modern London.
Mexico City
Due to its location in a highland "bowl", cold air sinks down onto the urban area of Mexico City, trapping industrial and vehicle pollution underneath, and turning it into the most infamously smog-plagued city of Latin America. Within one generation, the city has changed from being known for some of the cleanest air of the world into one with some of the worst pollution, with pollutants like nitrogen dioxide being double or even triple international standards.[14]
Santiago (Chile)
Similar to Mexico City, the air pollution of Santiago valley located between the Andes and Chilean Coast Range turning it into the most infamously smog-plagued city of South America. Other aggravant of the situation resides in its high latitude (31 degrees South) and dry weather at most part of the year.
Tehran
In December 2005, schools and public offices had to close in Tehran, Iran and 1600 people were taken to hospital, in a severe smog blamed largely on unfiltered car exhaust.[15]
United States
Smog was brought to the attention of the general US public in 1933 with the publication of the book "Stop That Smoke", by Henry Obermeyer, a New York public utility official, in which he pointed out the effect on human life and even the destruction of 3,000 acres (12 km²) of a farmer's spinach crop.[16] Since then, the United States Environmental Protection Agency has designated over 300 U.S. counties to be non-attainment areas for one or more pollutants tracked as part of the National Ambient Air Quality Standards.[17] These areas are largely clustered around large metropolitan areas, with the largest contiguous non-attainment zones in California and the Northeast. Various U.S. and Canadian government agencies collaborate to produce real-time air quality maps and forecasts.[18]
Los Angeles and the San Joaquin Valley
Being in low basins surrounded by mountains, Los Angeles and the San Joaquin Valley are notorious for their smog. The millions of vehicles in these basins plus the added effects of the San Francisco Bay and Los Angeles/Long Beach port complexes contribute to further air pollution. While strict regulations by the multiple California government agencies overseeing this problem have reduced the number of Stage 1 smog alerts from several hundred annually to just a few, these geologically predisposed entrapment zones collect pollution levels from cars, trucks and fixed sources which still exceeds health standards and is a pressing issue for the more than 25 million people who live there.
Major incidents in the US
- 1948, October 30–31, Donora, PA: 20 died, 600 hospitalized, thousands more stricken. Lawsuits were not settled until 1951.[19]
- 1953, November, New York: Smog kills between 170 and 260 people.[19]
- 1954, October, Los Angeles: heavy smog shuts down schools and industry for most of the month.[19]
- 1963, New York: blamed for 200 deaths[20]
- 1966, New York: blamed for 169 deaths[20]
Southeast Asia
See also: Asian brown cloud
Smog is a regular problem in Southeast Asia caused by land and forest fires in Indonesia, especially Sumatra and Kalimantan, although the term haze is preferred in describing the problem. Farmers and plantation owners are usually responsible for the fires, which they use to clear tracts of land for further plantings. Those fires mainly affect Brunei, Indonesia, Philippines, Malaysia, Singapore and Thailand, and occasionally Guam and Saipan.[21][22] The economic losses of the fires in 1997 have been estimated at more than US$9 billion.[23] This includes damages in agriculture production, destruction of forest lands, health, transportation, tourism, and other economic endeavours. Not included are social, environmental, and psychological problems and long-term health effects. The latest bout of haze to occur in Malaysia, Singapore and the Malacca Straits is in October 2006, and was caused by smoke from fires in Indonesia being blown across the Straits of Malacca by south-westerly winds.
The Association of Southeast Asian Nations (ASEAN) reacted and signed Agreement on Transboundary Haze Pollution, formed a Regional Haze Action Plan (RHAP) and established a co-ordination and support unit (CSU).[24] RHAP, with the help of Canada, established a monitoring and warning system for forest/vegetation fires and implemented a Fire Danger Rating System (FDRS). The Malaysian Meteorological Service (MMS)[25] has issued a daily rating since September 2003. The Indonesians have been ineffective at enforcing legal policies on errant farmers.
Natural causes
An erupting volcano can also emit high levels of sulphur dioxide along with a large quantity of particulate matter; two key components to the creation of smog. However, the smog created as a result of a volcanic eruption is often known as "vog"[citation needed] to distinguish it as a natural occurrence.
The radiocarbon content of some plant life has been linked to the distribution of smog in some areas. For example; presence of Creosote bush in the Los Angeles area has been shown to have an effect on smog distribution that is more than fossil fuel combustion alone.[26]
Pollution index
The severity of smog is often measured using automated optical instruments such as Nephelometers, as haze is associated with visibility and traffic control in ports. Haze however can also be an indication of poor air quality though this is often better reflected using accurate purpose built air indexes such as the American Air Quality Index, the Malaysian API (Air Pollution Index) and the Singaporean Pollutant Standards Index.
In hazy conditions, it is likely that the index will report the suspended particulate level. The disclosure of the responsible pollutant is mandated in some jurisdictions.
The Malaysian API does not have a capped value; hence its most hazardous readings can go above 500. Above 500, a state of emergency is declared in the affected area. Usually, this means that non-essential government services are suspended, and all ports in the affected area are closed. There may also be prohibitions on private sector commercial and industrial activities in the affected area excluding the food sector. So far, state of emergency rulings due to hazardous API levels were applied to the Malaysian towns of Port Klang, Kuala Selangor and the state of Sarawak during the 2005 Malaysian haze and the 1997 Southeast Asian haze.
Cultural references
- The London "pea-soupers" earned the capital the nickname of "The Smoke". Similarly, Edinburgh was known as "Auld Reekie". The smogs feature in many London novels as a motif indicating hidden danger or a mystery, perhaps most overtly in Margery Allingham's The Tiger in the Smoke (1952), but also in Dickens' Bleak House (1852) and T.S. Eliot's The Love Song of J. Alfred Prufrock.
- The 1970 made-for-TV movie A Clear and Present Danger, which featured Hal Holbrook, E.G. Marshall, Joseph Campanella, Jack Albertson and Pat Hingle, was one of the first American television network entertainment programs to warn about the problem of smog and air pollution.[27]
- Hedorah, a monster from the Godzilla movie, Godzilla vs. Hedorah, feeds on pollution and is referred to as "The Smog Monster".
- South Park, The town of South park is beset by smug, in the episode Smug Alert!, a satirical reference to both smog and celebrities who wish to prevent environmental degradation.
- The history of smog in LA is detailed in Smogtown by Chip Jacobs and William J. Kelly (Overlook Press).[28]
See also
- 1997 Southeast Asian haze
- 2005 Malaysian haze
- 2006 Southeast Asian haze
- Contrail
- Criteria air contaminants
- Emission standard
- Inversion effect
- Nitric oxide
- Ozone
- Umweltzone
References
- ^ Schwartz Cowan, Ruth (1997). A Social History of American Technology. Oxford University Press. ISBN 978-0-19-504605-2.
- ^ Gaia Piazzesi 2006
- ^ "What is Smog?", Canadian Council of Ministers of the Environment, CCME.ca
- ^ Miller, Jr., George Tyler (2002). Living in the Environment: Principles, Connections, and Solutions (12th Edition). Belmont: The Thomson Corporation. pp. 423. ISBN 0-534-37697-5.
- ^ USA Today
- ^ Airnow.gov, "Who is most at risk from ozone?"
- ^ CWAC.net, Ozone in Wisconsin
- ^ Airnow.gov
- ^ EPA.gov
- ^ Wheels.ca, $3.83 to power hybrid plug-in for 6 days
- ^ NPR.org, Smoggy Skies May Cause Respiratory Death
- ^ Environmentalgraffiti.com, Environmentalism in 1306
- ^ Bell, Michelle L.; Michelle L. Bell, Devra L. Davis, Tony Fletcher (January 2004). "A Retrospective Assessment of Mortality from the London Smog Episode of 1959: The Role of Influenza and Pollution". Environ Health Perspect 112 (1): 6–8. doi:10.1289/ehp.6539. PMC 1241789. PMID 14698923. http://www.ehponline.org/members/2003/6539/6539.html.
- ^ SBC.ac.at, Air pollution in Mexico City, University of Salzburg
- ^ "Hundreds treated over Tehran smog". BBC News. 2005-12-10. http://news.bbc.co.uk/1/hi/world/middle_east/4516430.stm. Retrieved 2006-08-03.
- ^ "Cities Unit in Concerted Drive Again Air Laden With Health Destroying Impurities", October 1933, Popular Science
- ^ EPA.gov, The Green Book Nonattainment Areas, Green Book |
- ^ Airnow.gov
- ^ a b c Radford.edu, Environmental History Timeline: 1940-1960
- ^ a b Washingtonpost.com
- ^ SaigpanTribune.com
- ^ Sun2Surf.com
- ^ Asean.org, ASEAN secreatriat on smog cost
- ^ Asean.org
- ^ KJC.gov.my
- ^ http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V7X-48XDN58-3H-1&_cdi=5854&_user=7209612&_pii=0160412081901136&_origin=search&_coverDate=12%2F31%2F1981&_sk=999949998&view=c&wchp=dGLzVzz-zSkzV&md5=b5a34a715396bf9618677e5f389bd00b&ie=/sdarticle.pdf
- ^ IMDb.com, A Clear and Present Danger (1970) (TV)
- ^ Overlookpress.com, Smogtown, The Lung-Burning History of Pollution in Los Angeles by Chip Jacobs & William J. Kelly
External links
 |
Wikimedia Commons has media related to: Smog |
- Smog A Citizendium article
- Eoearth.org, London Smog Disaster, Encyclopedia of Earth
- NPI.gov.au, National Pollutant Inventory - Particulate matter fact sheet
- Contrails.nl, Pictures of Contrails and Aviation Cirrus (- Smog), since 1995 until now.
- Ausetute.com.au, Photochemical Smog
- Iras.uu.nl, Airnet Workgroup Toxicology Report
- News
- BBC.co.uk, "When smog was a frequent occurrence, WW2 People's War, BBC 2005-08-10. Accessed 2006-08-03.
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Translations:
Top
Smog
Dansk (Danish)
n. - luftforurening, røgtåge, smog
Nederlands (Dutch)
smog, vuile mist
Ελληνική (Greek)
n. - αιθαλομίχλη, "νέφος"
Português (Portuguese)
n. - mistura de nevoeiro e fumaça
Русский (Russian)
смог, туман с дымом, окутывать смогом
Español (Spanish)
n. - smog, niebla espesa con humo
中文（简体）(Chinese (Simplified))
烟雾
中文（繁體）(Chinese (Traditional))
n. - 煙霧
العربيه (Arabic)
(الاسم) مزيج من ألضباب والدخان
עברית (Hebrew)
n. - ערפיח, ערפל ועשן
If you are unable to view some languages clearly, click here.
Post a question - any question - to the WikiAnswers community:
Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
Read more
Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
McGraw-Hill Science & Technology Encyclopedia
McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.
Read more
Gale Encyclopedia of Public Health
Encyclopedia of Public Health. Copyright © 2002 by The Gale Group, Inc. All rights reserved.
Read more
Oxford Dictionary of Geography
A Dictionary of Geography. Copyright © Susan Mayhew 1992, 1997, 2004. All rights reserved.
Read more
Columbia Encyclopedia
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2012, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/.
Read more
Dictionary of Cultural Literacy: Science
The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved.
Read more
McGraw-Hill Dictionary of Aviation
An Illustrated Dictionary of Aviation.. Copyright © 2005 by McGraw-Hill Companies, Inc. All rights reserved.
Read more
Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
Read more
Random House Word Menu
© 2010 Write Brothers Inc. Word Menu is a registered trademark of the Estate of Stephen Glazier.
Write Brothers Inc.
All rights reserved.
Read more
Wikipedia on Answers.com
This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Smog.
Read more
