Smog
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- For the rock band named Smog, see Smog (band).
Smog is a kind of air pollution - the name is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area and is caused by a mixture of smoke and sulphur dioxide. In the 1950s a new type of smog, known as photochemical smog, was first described. This is a noxious mixture of air pollutants including the following:
- nitrogen oxides, such as nitrogen dioxide
- tropospheric ozone
- volatile organic compounds (VOCs)
- peroxyacyl nitrates (PAN)
All of these chemicals are usually highly reactive and oxidizing. Due to this fact, photochemical smog is considered to be a problem of modern industrialization.
Photochemical smog is a concern in most major urban centres but, because it travels with the wind, it can affect sparsely populated areas as well. Smog is caused by a reaction between sunlight and emissions mainly from human activity. Photochemical smog is the chemical reaction of sunlight, nitrogen oxides (NOx) and volatile organic compounds (VOC's) in the atmosphere, which leaves airborne particles (called particulate matter) and ground-level ozone. Nitrogen oxides are released in the exhaust of fossil fuel-burning engines in cars, trucks, coal power plants, and industrial manufacturing factories. VOC's are vapors released from gasoline, paints, solvents, pesticides, and other chemicals.
'Smog' or 'Smoggy' has also come into use to describe a resident of Teesside (in North East England) or a supporter of Middlesbrough Football Club, due to the high concentration of chemical and heavy industry in the Teesside area.
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Origin of term
The term "smog" was first coined by Dr. Henry Antoine Des Voeux in his 1905 paper, “Fog and Smoke,” for a meeting of the Public Health Congress. The 26 July 1905 edition of the London newspaper Daily Graphic quoted Des Voeux, “[H]e 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 following day the newspaper stated that “Dr. Des Voeux did a public service in coining a new word for the London fog.”
Areas affected
Smog can form in almost any climate where industries or cities release large amounts of air pollution. 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, such as London, Los Angeles, Mexico City, Athens, Beijing, Hong Kong or the Ruhr Area and can build up to dangerous levels.
The high density of factories located in Mainland China has polluted Hong Kong. Now, Hong Kong's skyscrapers can barely be seen.
London
Even in the Middle Ages, concerns over air pollution were sufficient for Edward I to (briefly) ban the use of coal fires in London in 1273. In 1661, John Evelyn's Fumifugium suggested burning fragrant wood instead of mineral coal, to reduce coughing. A ballad of the time describes how the smoke "does our lungs and spirits choke, Our hanging spoil, and rust our iron." Template:NamedRef
Episodes of smog became common in London in the late 19th century and were nicknamed "pea-soupers". The Great Smog of 1952 darkened the skies over London and killed approximately 4,000 people in the short term (a further 8,000 died from its effects in the following weeks and months). Reluctant to admit that coal smoke was to blame, the British government initially blamed a flu epidemic. In 1956 the Clean Air Act introduced smokeless zones to the capital. Only smokeless fuels could be used in these areas. Consequently, reduced sulfur dioxide levels made the intense and persistent London smog a thing of the past. Smog caused by traffic pollution, however, does occur in modern London.
Health effects
Smog is a problem in a number of cities and continues to harm human health [1]. Ground-level ozone is especially harmful for seniors, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma[2]. It can inflame breathing passages, decreasing the lung's working capacity, and causing shortness of breath, pain when inhaling deeply, wheezing, and coughing. It can cause eye and nose irritation and dry out the protective membranes of the nose and throat and interfere 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 [3].
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" [4]. The "very unhealthy" range for some other pollutants are: 355 μg m-3 - 424 μg m-3 for PM10; 15.5 ppbv - 30.4ppb for CO and 0.65 ppbv - 1.24 [5]
Image:Golden Gate Bridge 2003.jpg
Natural causes
An erupting volcano can also emit high levels of sulfur dioxide, creating volcanic smog, or vog.
The burning of forests in Indonesia has on a number of occasions created prolonged smog-like haze, which have extended to parts of Malaysia, Philippines, Singapore and Thailand.
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).
[A]s he handed me into a fly after superintending the removal of my boxes, I asked him whether there was a great fire anywhere? For the streets were so full of dense brown smoke that scarcely anything was to be seen.
"Oh, dear no, miss," he said. "This is a London particular."
I had never heard of such a thing.
"A fog, miss," said the young gentleman.
— Dickens, Bleak House
See also
Notes and references
External links
de:Smog es:Smog fr:Smog he:ערפיח hu:Szmog it:Smog ja:スモッグ ms:asbut nl:Smog oc:Esmòg pl:Smog sv:Smog