Editing Smog (section)

==== United States ====
[[File:Upstatenysmog.jpg|thumb|right|A [[NASA]] astronaut's photograph of a smog layer over central [[New York (state)|New York]]]]
[[File:LAcityhalllookingsouth8.JPG|thumb|right|View of smog south from [[Los Angeles City Hall]], September 2011]]
[[File:US Counties Designated Non-attainment according to EPA NAAQS.jpg|thumb|right|Counties in the United States where one or more [[National Ambient Air Quality Standards]] are not met, as of October 2015]]
Smog was brought to the attention of the general U.S. 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 {{convert|3000|acre|km2}} of a farmer's spinach crop.<ref>{{Cite web|url=https://books.google.com/books?id=6CcDAAAAMBAJ&q=motor+gun+boat&pg=PA29|title=Popular Science|date=10 October 1933|publisher=Bonnier Corporation|via=Google Books}}</ref> 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]].<ref>[http://www.epa.gov/oar/oaqps/greenbk/ EPA.gov<!-- Bot generated title -->], The Green Book Nonattainment Areas, Green Book |</ref> 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 [[Air pollution forecasting|forecasts]].<ref>{{cite web | url = http://www.airnow.gov/index.cfm?action=topics.about_airnow | title = About AIRNow | date = 6 May 2013 | publisher = AIRNow | access-date = 25 October 2013 | archive-url = https://web.archive.org/web/20131029190708/http://www.airnow.gov/index.cfm?action=topics.about_airnow | archive-date = 29 October 2013 | url-status = dead }}</ref> To combat smog conditions, localities may declare "smog alert" days, such as in the [[Spare the Air program]] in the [[San Francisco Bay Area]]. By 1970, Congress enacted the Clean Air Act to regulate air pollutant emissions.<ref>{{Cite web |last=US EPA |first=OP |date=2013-02-22 |title=Summary of the Clean Air Act |url=https://www.epa.gov/laws-regulations/summary-clean-air-act |access-date=2022-03-13 |website=www.epa.gov |language=en}}</ref>

In the United States, smog pollution kills 24,000 Americans every year. The U.S. is among the dirtier countries in terms of smog, ranked 123 out of 195 countries measured, where 1 is cleanest and 195 is most smog polluted.<ref>Associated Press, 5 June 2019, [https://www.apnews.com/a2e7024d43c9409087ec8d5245534092 "AP Fact Check: Trump Didn't Set Records on Clean Air in US"]</ref>

====={{anchor|LA}}Los Angeles and the San Joaquin Valley=====
Because of their locations in low basins surrounded by mountains, [[Los Angeles]] and the [[San Joaquin Valley]] are notorious for their smog. Heavy automobile traffic, combined with the additional effects of the [[San Francisco Bay]] and Los Angeles/[[Long Beach, California|Long Beach]] port complexes, frequently contribute to further air pollution.

Los Angeles, in particular, is strongly predisposed to the accumulation of smog, because of the peculiarities of its geography and weather patterns. Los Angeles is situated in a flat basin with the ocean on one side and mountain ranges on three sides. A nearby cold ocean current depresses surface air temperatures in the area, resulting in an [[Inversion (meteorology)|inversion layer]]: a phenomenon where air temperature increases, instead of decreasing, with altitude, suppressing [[thermals]] and restricting vertical convection. All taken together, this results in a relatively thin, enclosed layer of air above the city that cannot easily escape out of the basin and tends to accumulate pollution.

Los Angeles was one of the best-known cities suffering from transportation smog for much of the 20th century, so much so that it was sometimes said that ''Los Angeles'' was a synonym for ''smog.''<ref>{{cite book|title=The Economics and Politics of the Slowdown in Regulatory Reform|author=Roger G. Noll|year=1999}}</ref> In 1970, when the Clean Air Act was passed, Los Angeles was the most polluted basin in the country, and California was unable to create a State Implementation Plan that would enable it to meet the new air quality standards.<ref>"Early Implementation of the Clean Air Act of 1970 in California." EPA Alumni Association. [http://www.epaalumni.org/history/video/interview.cfm?id=38 Video], [https://www.epaalumni.org/userdata/pdf/2B9E3C6816EC9466.pdf#page=1 Transcript] (see p6). 12 July 2016.</ref> However, ensuing strict regulations by state and federal government agencies overseeing this problem (such as the [[California Air Resources Board]] and the [[United States Environmental Protection Agency]]), including tight restrictions on allowed emissions levels for all new cars sold in California and mandatory regular emission tests of older vehicles, resulted in significant improvements in air quality.<ref>{{Cite web|last=US EPA|first=OAR|date=2016-05-05|title=Vehicle Emissions California Waivers and Authorizations|url=https://www.epa.gov/state-and-local-transportation/vehicle-emissions-california-waivers-and-authorizations|access-date=2020-11-26|website=US EPA|language=en}}</ref> For example, air concentrations of volatile organic compounds declined by a factor of 50 between 1962 and 2012.<ref>{{Cite web|url=https://csl.noaa.gov/news/2012/119_0809.html|title=NOAA CSL: 2012 News & Events: 50-year decline in some Los Angeles vehicle-related pollutants|first=NOAA Chemical Sciences|last=Laboratory (CSL)|website=csl.noaa.gov}}</ref> Concentrations of air pollutants such as nitrous oxides and ozone declined by 70% to 80% over the same period of time.<ref>{{cite web|url=http://hbsciu.com/2015/02/15/is-clean-air-worth-the-cost-a-case-study-for-developing-megacities-2/|title=Is clean air worth the cost? A case study for developing megacities|work=HBSciU |date=15 February 2015}}</ref>

===== Major incidents in the U.S. =====
* 26 July 1943, [[Los Angeles, California]]: A smog so sudden and severe that "Los Angeles residents believe the Japanese are attacking them with chemical warfare."<ref>{{cite magazine | date = 2010 | url = https://www.wired.com/2010/07/0726la-first-big-smog/ | title = July 26, 1943: L.A. Gets First Big Smog | author = Jess McNally | magazine = Wired}}</ref><ref>{{cite book |last=Buntin |first=John |title=L.A. Noir: The Struggle for the Soul of America's Most Seductive City |url=https://books.google.com/books?id=PIHClVp5F4AC |access-date=12 October 2014 |year=2009 |publisher=Harmony Books |location=New York |isbn=9780307352071 |oclc=431334523 |page=108}}</ref>
* [[1948 Donora smog|30-31 October 1948]], [[Donora, Pennsylvania]]: 20 died, 600 hospitalized, thousands more stricken. Lawsuits were not settled until 1951.<ref name="autogenerated2">{{cite web | date = 1948 | url = http://www.radford.edu/~wkovarik/envhist/7forties.html | title = World War II and the Postwar Years | publisher = Environmental History Timeline | url-status = dead | archive-url = https://web.archive.org/web/20110205085302/http://www.radford.edu/~wkovarik/envhist/7forties.html | archive-date = 5 February 2011 }}</ref>
* [[1966 New York City smog|24 November 1966]], [[New York City, New York]]: Smog kills at least 169<ref>{{cite news|url=https://www.washingtonpost.com/blogs/capital-weather-gang/post/the-killer-london-smog-event-of-december-1952-a-reminder-of-deadly-smog-events-in-us/2012/12/19/452c66bc-498e-11e2-b6f0-e851e741d196_blog.html |title=The Killer London Smog Event of December 1952: A Reminder of Deadly Smog Events in the US |last=Tracton |first=Steve |newspaper=The Washington Post |date=20 December 2012 |access-date=25 February 2015}}</ref> people.