Photochemical smog - Revision history

Jmdonev: 1 revision imported

2018-09-03T22:23:31Z

1 revision imported

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energy>Jmdonev at 21:57, 25 July 2018

2018-07-25T21:57:52Z

← Older revision		Revision as of 21:57, 25 July 2018
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	[[Category:Done ~~2015~~-07-24]]		[[Category:Done 2018-08-03]]
	[[File:shanghai.jpg\|300px\|thumb\|Figure 1. Photochemical smog over Shanghai.<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/d/d1/Shanghaiairpollutionsunset.jpg</ref>]]		[[File:shanghai.jpg\|300px\|thumb\|Figure 1. Photochemical smog over Shanghai.<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/d/d1/Shanghaiairpollutionsunset.jpg</ref>]]

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	===Composition===		===Composition===

	Nitric oxide (NO) and nitrogen dioxide (NO<sub>2</sub>) are emitted from the combustion of [[fossil fuel]]s, along with being naturally emitted from things such as volcanos and forest fires (it is the ''immense concentration'' of these pollutants within cities that is of the most concern however, as natural emissions tend to spread out over larger areas). When exposed to ultraviolet radiation, NO<sub>2</sub> goes through a complex series of reactions with [[hydrocarbon]]s to produce the components of photochemical ~~smog -- a~~ mixture of '''[[ozone]]''', '''nitric acid''', '''aldehydes''', '''[[peroxyacyl nitrate]]s''' ('''PANs''') and other [[secondary pollutant]]s.<Ref name=hackett/>		Nitric oxide (NO) and nitrogen dioxide (NO<sub>2</sub>) are emitted from the combustion of [[fossil fuel]]s, along with being naturally emitted from things such as volcanos and forest fires (it is the ''immense concentration'' of these pollutants within cities that is of the most concern however, as natural emissions tend to spread out over larger areas). When exposed to ultraviolet radiation, NO<sub>2</sub> goes through a complex series of reactions with [[hydrocarbon]]s to produce the components of photochemical smog—a mixture of '''[[ozone]]''', '''nitric acid''', '''aldehydes''', '''[[peroxyacyl nitrate]]s''' ('''PANs''') and other [[secondary pollutant]]s.<Ref name=hackett/>

	NO<sub>2</sub>, ozone and PANs are called '''photochemical oxidants''' because they can react ~~with~~ and oxidize certain compounds in the atmosphere or within a person's lungs that are not normally oxidized. Even small traces of these chemicals can affect the respiratory tract of humans and animals, and damage crops and trees.<Ref name=hackett/>		NO<sub>2</sub>, ozone and PANs are called '''photochemical oxidants''' because they can react and oxidize certain compounds in the atmosphere or within a person's lungs that are not normally oxidized. Even small traces of these chemicals can affect the respiratory tract of humans and animals, and damage crops and trees.<Ref name=hackett/>

	[[File:photochemsmog.png\|thumb\|800px\|center\|Figure 2. Photochemical smog formation; sunlight reacts with NO<sub>2</sub> which then interacts with other molecules in the air to form smog.<ref>Adapted from Living In The Environment. See Reference 4.</ref>]]		[[File:photochemsmog.png\|thumb\|800px\|center\|Figure 2. Photochemical smog formation; sunlight reacts with NO<sub>2</sub> which then interacts with other molecules in the air to form smog.<ref>Adapted from Living In The Environment. See Reference 4.</ref>]]
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	Ground level ozone is also produced which has various effects on the human body. For more information, visit the [[ozone]] page.		Ground level ozone is also produced which has various effects on the human body. For more information, visit the [[ozone]] page.

			==For Further Reading==
			*[[Ultraviolet]]
			*[[Smog]]
			*[[Atmosphere]]
			*[[Pollutant]]
			*[[Hydrocarbon combustion]]
			*Or explore a [[Special:Random\|random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:31:30Z

1 revision imported

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J.williams at 16:58, 12 August 2015

2015-08-12T16:58:31Z

New page

[[Category:Done 2015-07-24]]
[[File:shanghai.jpg|300px|thumb|Figure 1. Photochemical smog over Shanghai.<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/d/d1/Shanghaiairpollutionsunset.jpg</ref>]]

<onlyinclude>'''Photochemical smog''' is a type of [[smog]] produced when [[ultraviolet]] light from the [[sun]] reacts with [[NOx|nitrogen oxides]] in the [[atmosphere]]. It is visible as a brown haze, and is most prominent during the morning and afternoon, especially in densely populated, warm cities.</onlyinclude><Ref name=boyle>B. Everett, G. Boyle, S. Peake and J. Ramage, "," in "Penalties: Assessing the Environmental and Health Impacts of Energy Use," in ''Energy Systems and Sustainability'', 2nd ed., Oxford, UK: Oxford, 2013, ch.13, pp.543</ref> Cities that experience this smog daily include Los Angeles, Sydney, Mexico City, Beijing, and many more.

==Formation==

Photochemical smog forms from a complex process, however the source of it is quite apparent. The largest contributor is automobiles, while [[coal-fired power plant]]s and some other power plants also produce the necessary [[pollutant]]s to facilitate its production. Due to its abundance in areas of warmer [[temperature]]s, photochemical smog is most common in the summer.<ref name=hinrichs>R. A. Hinrichs and M. Kleinbach, "Nitrogen oxides, photochemical smog and ozone," in ''Energy: Its Use and the Environment'', 5th ed. Toronto, Ont. Canada: Brooks/Cole, 2013, ch.8, sec.C, pp.250-252</ref>

It forms in the morning when a tremendous number people are driving their vehicles to work. Nitrogen oxides produced in the car [[engine]] are introduced into the atmosphere, which may combine with [[water]] to form nitric acid or react with sunlight to produce singular [[oxygen]] atoms, which then combine with [[molecular oxygen]] to produce [[ozone]].<ref name=boyle/> The nitric acid may precipitate to the Earth resulting in [[acid rain]], or remain in the smog. Due to the direct production of it by vehicles, the smog forms over cities where many people may encounter its adverse health effects.

Hotter days mean more photochemical smog, especially in the densely populated cities such as those mentioned above. As more and more [[urban population]]s arise around the globe, this problem is only expected to increase.<ref name=hackett>G. Tyler Miller, Jr. and D. Hackett, "Photochemical and Industrial Smog," in ''Living in the Environment'', 2nd ed. USA: Nelson , 2011, ch.20, sec.3, pp.465-471</ref>

===Composition===

Nitric oxide (NO) and nitrogen dioxide (NO2) are emitted from the combustion of [[fossil fuel]]s, along with being naturally emitted from things such as volcanos and forest fires (it is the ''immense concentration'' of these pollutants within cities that is of the most concern however, as natural emissions tend to spread out over larger areas). When exposed to ultraviolet radiation, NO2 goes through a complex series of reactions with [[hydrocarbon]]s to produce the components of photochemical smog -- a mixture of '''[[ozone]]''', '''nitric acid''', '''aldehydes''', '''[[peroxyacyl nitrate]]s''' ('''PANs''') and other [[secondary pollutant]]s.<Ref name=hackett/>

NO2, ozone and PANs are called '''photochemical oxidants''' because they can react with and oxidize certain compounds in the atmosphere or within a person's lungs that are not normally oxidized. Even small traces of these chemicals can affect the respiratory tract of humans and animals, and damage crops and trees.<Ref name=hackett/>

[[File:photochemsmog.png|thumb|800px|center|Figure 2. Photochemical smog formation; sunlight reacts with NO2 which then interacts with other molecules in the air to form smog.<ref>Adapted from Living In The Environment. See Reference 4.</ref>]]

==Effects==

Photochemical smog has many adverse effects. When combined with hydrocarbons, the chemicals contained within it form [[molecule]]s that cause eye irritation. Radicals in the air interfere with the [[nitrogen]] cycle by preventing the destruction of ground level ozone. Other effects include reduced visibility and respiratory ailments.<ref name=hinrichs/>

Ground level ozone is also produced which has various effects on the human body. For more information, visit the [[ozone]] page.

==References==
{{reflist}}
[[Category:Uploaded]]