ozone layer

{{Main|Ozone–oxygen cycle}}

File:Ozone cycle.svg in the ozone layer]]

The Earth's ozone layer formed about 500 million years ago, when the neoproterozoic oxygenation event brought the fraction of oxygen in the atmosphere to about 20%.{{cite web|url=https://www.discovermagazine.com/environment/how-the-ozone-layer-evolved-and-why-its-important|title=How the Ozone Layer Evolved and Why It's Important |author=Paul M. Sutter |date=July 20, 2023 |publisher=Discover Magazine}}

The photochemical mechanisms that give rise to the ozone layer were discovered by the British physicist Sydney Chapman in 1930. Ozone in the Earth's stratosphere is created by ultraviolet light striking ordinary oxygen molecules containing two oxygen atoms (O₂), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O₂ to create ozone, O₃. The ozone molecule is unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O₂ and an individual atom of oxygen, a continuing process called the ozone–oxygen cycle. Chemically, this can be described as:

: O2{} + \mathit{h}\nu_{uv} -> 2O

: O + O2 <-> O3

About 90% of the ozone in the atmosphere is contained in the stratosphere. Ozone concentrations are greatest between about {{convert|20|and|40|km|ft}}, where they range from about 2 to 8 parts per million. If all of the ozone were compressed to the pressure of the air at sea level, it would be only {{convert|3|mm|in|abbr=off|frac=8}} thick.{{cite web |title=NASA Facts Archive |url=http://www.nasa.gov/facts/Earth/earth_facts_archives.html |access-date=June 9, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20130406065500/http://www.nasa.gov/facts/Earth/earth_facts_archives.html |archive-date=April 6, 2013}}

File:Ozone solar UV absorb DNA action.jpg

File:Ozone altitude UV graph.svg of dioxygen (below 240 nm) react with more dioxygen. The ozone layer also blocks most, but not quite all, of the sunburn-producing UV-B (280–315 nm) band, which lies in the wavelengths longer than UV-C. The band of UV closest to visible light, UV-A (315–400 nm), is hardly affected by ozone, and most of it reaches the ground. UV-A does not primarily cause skin reddening, but there is evidence that it causes long-term skin damage.]]

Although the concentration of the ozone in the ozone layer is very small, it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation coming from the Sun. Extremely short or vacuum UV (10–100 nm) is screened out by nitrogen. UV radiation capable of penetrating nitrogen is divided into three categories, based on its wavelength; these are referred to as UV-A (400–315 nm), UV-B (315–280 nm), and UV-C (280–100 nm).

UV-C, which is very harmful to all living things, is entirely screened out by a combination of dioxygen (< 200 nm) and ozone (> about 200 nm) by around {{convert|35|km|ft}} altitude. UV-B radiation can be harmful to the skin and is the main cause of sunburn; excessive exposure can also cause cataracts, immune system suppression, and genetic damage, resulting in problems such as skin cancer. The ozone layer (which absorbs from about 200 nm to 310 nm with a maximal absorption at about 250 nm){{cite journal |title=Photolysis of Atmospheric Ozone in the Ultraviolet Region |author1=Matsumi, Y. |author2=Kawasaki, M. |journal=Chem. Rev. |date=2003 |volume=103 |issue=12 |pages=4767–4781 |pmid=14664632 |doi=10.1021/cr0205255 |url=http://yly-mac.gps.caltech.edu/N2O/Prasad/Matsumi_O3_cr0205255%20copy.pdf |access-date=March 14, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20120617123007/http://yly-mac.gps.caltech.edu/N2O/Prasad/Matsumi_O3_cr0205255%20copy.pdf |archive-date=June 17, 2012}} is very effective at screening out UV-B; for radiation with a wavelength of 290 nm, the intensity at the top of the atmosphere is 350 million times stronger than at the Earth's surface. Nevertheless, some UV-B, particularly at its longest wavelengths, reaches the surface, and is important for the skin's production of vitamin D in mammals.

Ozone is transparent to most UV-A, so most of this longer-wavelength UV radiation reaches the surface, and it constitutes most of the UV reaching the Earth. This type of UV radiation is significantly less harmful to DNA, although it may still potentially cause physical damage, premature aging of the skin, indirect genetic damage, and skin cancer.{{cite journal |title=Review: Ultraviolet radiation and skin cancer |author1=Narayanan, D.L. |author2=Saladi, R.N. |author3=Fox, J.L. |journal=International Journal of Dermatology |volume=49 |issue=9 |pages=978–986 |date=2010 |pmid=20883261 |doi=10.1111/j.1365-4632.2010.04474.x |doi-access=free |s2cid=22224492}}

{{More citations needed section|date=February 2013}}

File:Atmosphere20Layers 2018.jpg

The thickness of the ozone layer varies worldwide and is generally thinner near the equator and thicker near the poles.{{cite book |title=Global Warming: The Effect Of Ozone Depletion |author=Tabin, Shagoon |publisher=APH Publishing |year=2008 |isbn=9788131303962 |page=194 |url=https://books.google.com/books?id=QFBmUu1lwzAC |access-date=January 12, 2016}} Thickness refers to how much ozone is in a column over a given area and varies from season to season. The reasons for these variations are due to atmospheric circulation patterns and solar intensity.{{cite web |title=Nasa Ozone Watch: Ozone facts |website=ozonewatch.gsfc.nasa.gov |url=https://ozonewatch.gsfc.nasa.gov/facts/SH.html |access-date=September 16, 2021}}

The ozone layer ends gradually, but in general its upper limit is where air becomes too thin for UV light to generate much ozone, and its lower limit is where generated ozone blocks enough UV light to stop most ozone production.

In the homosphere, wind-driven movement is more important than relative gas weight. The majority of ozone is produced over the tropics and is transported toward the poles by stratospheric wind patterns. In the northern hemisphere these patterns, known as the Brewer–Dobson circulation, make the ozone layer thickest in the spring and thinnest in the fall. When ozone is produced by solar UV radiation in the tropics, it is done so by circulation lifting ozone-poor air out of the troposphere and into the stratosphere where the sun photolyzes oxygen molecules and turns them into ozone. Then, the ozone-rich air is carried to higher latitudes and drops into lower layers of the atmosphere.

Research has found that the ozone levels in the United States are highest in the spring months of April and May and lowest in October. While the total amount of ozone increases moving from the tropics to higher latitudes, the concentrations are greater in high northern latitudes than in high southern latitudes, with spring ozone columns in high northern latitudes occasionally exceeding 600 DU and averaging 450 DU whereas 400 DU constituted a usual maximum in the Antarctic before anthropogenic ozone depletion. This difference occurred naturally because of the weaker polar vortex and stronger Brewer–Dobson circulation in the northern hemisphere owing to that hemisphere's large mountain ranges and greater contrasts between land and ocean temperatures.{{cite journal |author=Douglass |first1=Anne R. |last2=Newman |first2=Paul A. |last3=Solomon |first3=Susan |title=The Antarctic ozone hole: An update |journal=Physics Today |year=2014 |volume=67 |issue=7 |pages=42–48 |publisher=American Institute of Physics |bibcode=2014PhT....67g..42D |doi=10.1063/PT.3.2449 |hdl=1721.1/99159 |hdl-access=free |url=https://physicstoday.scitation.org/doi/pdf/10.1063/PT.3.2449}} The difference between high northern and southern latitudes has increased since the 1970s due to the ozone hole phenomenon. The highest amounts of ozone are found over the Arctic during the spring months of March and April, but the Antarctic has the lowest amounts of ozone during the summer months of September and October,

File:Nimbus ozone Brewer-Dobson circulation.jpg

{{Main|Ozone depletion}}

File:Future ozone layer concentrations.gifs had not been banned]]

The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), nitrous oxide (N₂O), hydroxyl (OH), atomic chlorine (Cl), and atomic bromine (Br). While there are natural sources for all of these species, the concentrations of chlorine and bromine increased markedly in recent decades because of the release of large quantities of man-made organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons.{{cite book |chapter-url=http://www.eia.doe.gov/oiaf/1605/archive/gg97rpt/chap5.html |chapter=Halocarbons and Other Gases |publisher=Energy Information Administration |title=Emissions of Greenhouse Gases in the United States 1996 |date=1997 |access-date=June 24, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080629032506/http://www.eia.doe.gov/oiaf/1605/archive/gg97rpt/chap5.html |archive-date=June 29, 2008}} Atmospheric components are not sorted out by weight in the homosphere because of wind-driven mixing that extends to an altitude of about 90 km, well above the ozone layer. So despite being heavier than diatomic nitrogen and oxygen, these highly stable compounds rise into the stratosphere, where Cl and Br radicals are liberated by the action of ultraviolet light. Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. By 2009, nitrous oxide was the largest ozone-depleting substance (ODS) emitted through human activities.{{cite web |title=NOAA Study Shows Nitrous Oxide Now Top Ozone-Depleting Emission |publisher=NOAA |date=August 27, 2009 |url=http://www.noaanews.noaa.gov/stories2009/20090827_ozone.html |access-date=November 8, 2011}}

The breakdown of ozone in the stratosphere results in reduced absorption of ultraviolet radiation. Consequently, unabsorbed and dangerous ultraviolet radiation reaches the Earth's surface at a higher intensity. Ozone levels have dropped by a worldwide average of about 4 percent since the late 1970s. For approximately 5 percent of the Earth's surface, around the north and south poles, much larger seasonal declines have been seen, and are described as "ozone holes". "Ozone holes" are actually patches in the ozone layer in which the ozone is thinner. The thinnest parts of the ozone are at the polar points of Earth's axis.{{cite web |title=ozone layer {{!}} National Geographic Society |url=https://education.nationalgeographic.org/resource/ozone-layer |access-date=May 30, 2022 |website=education.nationalgeographic.org}} The discovery of the annual depletion of ozone above the Antarctic was first announced by Joe Farman, Brian Gardiner, and Jonathan Shanklin, in a paper which appeared in Nature on May 16, 1985.

Regulation attempts have included but not have been limited to the Clean Air Act implemented by the United States Environmental Protection Agency. The Clean Air Act introduced the requirement of [https://www.epa.gov/criteria-air-pollutants/naaqs-table National Ambient Air Quality Standards (NAAQS)] with ozone pollutions being one of six criteria pollutants. This regulation has proven to be effective since counties, cities, and tribal regions must abide by these standards and the EPA also provides assistance for each region to regulate contaminants.{{cite web |last=US EPA |first=OAR |title=Ozone Implementation Regulatory Actions |date=December 14, 2016 |language=en |website=epa.gov |url=https://www.epa.gov/ground-level-ozone-pollution/ozone-implementation-regulatory-actions |access-date=May 30, 2022}} Effective presentation of information has also proven to be important in order to educate the general population of the existence and regulation of ozone depletion and contaminants. A scientific paper was written by Sheldon Ungar in which the author explores and studies how information about the depletion of the ozone, climate change, and various related topics. The ozone case was communicated to lay persons "with easy-to-understand bridging metaphors derived from the popular culture" and related to "immediate risks with everyday relevance".{{cite journal |last=Ungar |first=Sheldon |title=Knowledge, ignorance and the popular culture: climate change versus the ozone hole |date=July 2000 |journal=Public Understanding of Science |language=en |volume=9 |issue=3 |pages=297–312 |issn=0963-6625 |doi=10.1088/0963-6625/9/3/306 |s2cid=7089937 |url=https://journals.sagepub.com/doi/10.1088/0963-6625/9/3/306}} The specific metaphors used in the discussion (ozone shield, ozone hole) proved quite useful and, compared to global climate change, the ozone case was much more seen as a "hot issue" and imminent risk. Lay people were cautious about a depletion of the ozone layer and the risks of skin cancer.

Satellites burning up upon re-entry into Earth's atmosphere produce aluminum oxide (Al₂O₃) nanoparticles that endure in the atmosphere for decades. Estimates for 2022 alone were ~17 metric tons (~30{{nbsp}}kg of nanoparticles per ~250{{nbsp}}kg satellite). Increasing populations of satellite constellations can eventually lead to significant ozone depletion.{{cite journal |last1=Ferreira |first1=Jose P. |last2=Huang |first2=Ziyu |last3=Nomura |first3=Ken-ichi |last4=Wang |first4=Joseph |title=Potential Ozone Depletion From Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations |journal=Geophysical Research Letters |date=11 June 2024 |volume=51 |issue=11 |doi=10.1029/2024GL109280 |doi-access=free}}

"Bad" ozone{{Clarification needed|date=January 2025}} can cause adverse health risks respiratory effects (difficulty breathing) and is proven to be an aggravator of respiratory illnesses such as asthma, COPD, and emphysema.{{cite journal |last1=Zhang |first1=Junfeng (Jim) |last2=Wei |first2=Yongjie |last3=Fang |first3=Zhangfu |title=Ozone Pollution: A Major Health Hazard Worldwide |date=2019 |journal=Frontiers in Immunology |volume=10 |page=2518 |issn=1664-3224 |pmid=31736954 |doi=10.3389/fimmu.2019.02518 |doi-access=free |pmc=6834528}} That is why many countries have set in place regulations to improve "good" ozone{{Clarification needed|date=January 2025}} and prevent the increase of "bad" ozone in urban or residential areas. In terms of ozone protection (the preservation of "good" ozone) the European Union has strict guidelines on what products are allowed to be bought, distributed, or used in specific areas.{{cite web |title=Ozone Regulation |language=en |website=ec.europa.eu |url=https://ec.europa.eu/clima/eu-action/protection-ozone-layer/ozone-regulation_en |access-date=May 30, 2022}} With effective regulation, the ozone is expected to heal over time.{{cite web |last=US EPA |first=OAR |title=International Treaties and Cooperation about the Protection of the Stratospheric Ozone Layer |date=July 15, 2015 |language=en |website=epa.gov |url=https://www.epa.gov/ozone-layer-protection/international-treaties-and-cooperation-about-protection-stratospheric-ozone |access-date=May 30, 2022}}

File:TOMS Global Ozone 65N-65S.png

{{Main|Ozone depletion and climate change}}

In 1978, the United States, Canada, and Norway enacted bans on CFC-containing aerosol sprays that damage the ozone layer but the European Community rejected a similar proposal. In the U.S., chlorofluorocarbons continued to be used in other applications, such as refrigeration and industrial cleaning, until after the discovery of the Antarctic ozone hole in 1985. After negotiation of an international treaty (the Montreal Protocol), CFC production was capped at 1986 levels with commitments to long-term reductions.{{cite journal |title=The Evolution of Policy Responses to Stratospheric Ozone Depletion |journal=Natural Resources Journal |date=1989 |last=Morrisette |first=Peter M. |volume=29 |pages=793–820 |url=http://www.ciesin.org/docs/003-006/003-006.html |access-date=April 20, 2010}} This allowed for a ten-year phase-in for developing countriesAn Interview with Lee Thomas, EPA's 6th Administrator. [http://www.epaalumni.org/history/video/interview.cfm?id=28 Video], [https://www.epaalumni.org/userdata/pdf/60740780F5ACB3D5.pdf#page=1 Transcript] (see p15). April 19, 2012. (identified in Article 5 of the protocol). Since then, the treaty was amended to ban CFC production after 1995 in developed countries, and later in developing countries.{{cite web |title=Amendments to the Montreal Protocol |publisher=EPA |date=August 19, 2010 |url=http://www.epa.gov/ozone/intpol/history.html |access-date=March 28, 2011}} All of the world's 197 countries have signed the treaty. Beginning January 1, 1996, only recycled or stockpiled CFCs were available for use in developed countries like the US. The production phaseout was possible because of efforts to ensure that there would be substitute chemicals and technologies for all ODS uses.{{cite web |title=Brief Questions and Answers on Ozone Depletion |publisher=EPA |date=June 28, 2006 |url=http://www.epa.gov/ozone/science/q_a.html |access-date=November 8, 2011}}

On August 2, 2003, scientists announced that the global depletion of the ozone layer might be slowing because of the international regulation of ozone-depleting substances. In a study organized by the American Geophysical Union, three satellites and three ground stations confirmed that the upper-atmosphere ozone-depletion rate slowed significantly over the previous decade. Some breakdown was expected to continue because of ODSs used by nations which have not banned them, and because of gases already in the stratosphere. Some ODSs, including CFCs, have very long atmospheric lifetimes ranging from 50 to over 100 years. It has been estimated that the ozone layer will recover to 1980 levels near the middle of the 21st century.{{cite book |title=Scientific Assessment of Ozone Depletion: 2010 |date=2011 |publisher=WMO |chapter=Stratospheric Ozone and Surface Ultraviolet Radiation |chapter-url=http://acdb-ext.gsfc.nasa.gov/Documents/O3_Assessments/Docs/WMO_2010/Chapter_2.pdf |access-date=March 14, 2015}} A gradual trend toward "healing" was reported in 2016.{{cite journal |title=Emergence of healing in the Antarctic ozone layer |vauthors=Solomon, Susan etal |journal=Science |volume=353 |issue=6296 |pages=269–74 |date=June 30, 2016 |bibcode=2016Sci...353..269S |pmid=27365314 |doi=10.1126/science.aae0061 |doi-access=free |hdl=1721.1/107197 |hdl-access=free}}

Compounds containing C–H bonds (such as hydrochlorofluorocarbons, or HCFCs) have been designed to replace CFCs in certain applications. These replacement compounds are more reactive and less likely to survive long enough in the atmosphere to reach the stratosphere where they could affect the ozone layer. While being less damaging than CFCs, HCFCs can have a negative impact on the ozone layer, so they are also being phased out.{{cite web |title=Ozone Depletion Glossary |publisher=EPA |url=http://www.epa.gov/ozone/defns.html#hcfc |access-date=September 3, 2008}} These in turn are being replaced by hydrofluorocarbons (HFCs) and other compounds that do not destroy stratospheric ozone at all.

The residual effects of CFCs accumulating within the atmosphere lead to a concentration gradient between the atmosphere and the ocean. This organohalogen compound dissolves into the ocean's surface waters and acts as a time-dependent tracer. This tracer helps scientists study ocean circulation by tracing biological, physical, and chemical pathways.{{cite journal |title=Observations of CFCs and SF6 as Ocean Tracers |last=Fine |first=Rana A. |date=2011 |journal=Annual Review of Marine Science |volume=3 |pages=173–95 |bibcode=2011ARMS....3..173F |pmid=21329203 |doi=10.1146/annurev.marine.010908.163933 |url=http://yyy.rsmas.miami.edu/groups/cfc/pubs/Fine_AnnRevMarineSci3_2011.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150210212306/http://yyy.rsmas.miami.edu/groups/cfc/pubs/Fine_AnnRevMarineSci3_2011.pdf |archive-date=February 10, 2015}}

As ozone in the atmosphere prevents most energetic ultraviolet radiation reaching the surface of the Earth, astronomical data in these wavelengths have to be gathered from satellites orbiting above the atmosphere and ozone layer. Most of the light from young hot stars is in the ultraviolet and so study of these wavelengths is important for studying the origins of galaxies. The Galaxy Evolution Explorer, GALEX, is an orbiting ultraviolet space telescope launched on April 28, 2003, which operated until early 2012.{{cite web |title=ozone layer |date=May 9, 2011 |language=en |website=National Geographic Society |url=http://www.nationalgeographic.org/encyclopedia/ozone-layer/ |access-date=September 16, 2021}}

File:Ultraviolet image of the Cygnus Loop Nebula crop.jpg|This GALEX image of the Cygnus Loop nebula could not have been taken from the surface of the Earth because the ozone layer blocks the ultra-violet radiation emitted by the nebula.

• Cambrian explosion
• Nuclear winter
• Oxygen
• Short-lived climate pollutants
• United Nations Environment Programme

{{Reflist|33em}}

; Science

• {{cite journal |authorlink=Stephen O. Andersen |last=Andersen |first=S. O. |title=Lessons from the stratospheric ozone layer protection for climate |journal=Journal of Environmental Studies and Sciences |year=2015 |volume=5 |issue=2 |pages=143–162 |bibcode=2015JEnSS...5..143A |doi=10.1007/s13412-014-0213-9 |s2cid=129725437 |url=https://link.springer.com/article/10.1007/s13412-014-0213-9}}
• {{cite book |last1=Andersen |first1=S.O. |last2=Sarma |first2=K.M. |last3=Sinclair |first3=L. |title=Protecting the Ozone Layer: The United Nations History |publisher=Taylor & Francis |year=2012 |isbn=978-1-84977-226-6 |url=https://books.google.com/books?id=zuesUPcIOq8C}}
• Ritchie, Hannah, "What We Learned from Acid Rain: By working together, the nations of the world can solve climate change", Scientific American, vol. 330, no. 1 (January 2024), pp. 75–76. "[C]ountries will act only if they know others are willing to do the same. With acid rain, they did act collectively.... We did something similar to restore Earth's protective ozone layer.... [T]he cost of technology really matters.... In the past decade the price of solar energy has fallen by more than 90 percent and that of wind energy by more than 70 percent. Battery costs have tumbled by 98 percent since 1990, bringing the price of electric cars down with them....[T]he stance of elected officials matters more than their party affiliation.... Change can happen – but not on its own. We need to drive it." (p. 76.)
• United Nations Environment Programme (2010). Environmental Effects of Ozone Depletion and its Interactions with Climate Change: 2010 Assessment. Nairobi: UNEP.
• {{cite journal |title=The large contribution of projected HFC emissions to future climate forcing |year=2009 |last1=Velders |first1=G. J. M. |last2=Fahey |first2=D. W. |last3=Daniel |first3=J. S. |last4=McFarland |first4=M. |last5=Andersen |first5=S. O. |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=27 |pages=10949–10954 |bibcode=2009PNAS..10610949V |pmid=19549868 |doi=10.1073/pnas.0902817106 |doi-access=free |pmc=2700150 |s2cid=3743609}}
• {{cite journal |last1=Velders |first1=Guus J.M. |last2=Andersen |first2=Stephen O. |last3=Daniel |first3=John S. |last4=Fahey |first4=David W. |last5=McFarland |first5=Mack |year=2007 |title=The Importance of the Montreal Protocol in Protecting Climate |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=104 |issue=12 |pages=4814–4819 |bibcode=2007PNAS..104.4814V |pmid=17360370 |doi=10.1073/pnas.0610328104 |doi-access=free |pmc=1817831}}

; Policy

• {{cite journal |title=The importance of phasing down hydrofluorocarbons and other short-lived climate pollutants |year=2015 |last1=Zaelke |first1=Durwood |last2=Borgford-Parnell |first2=Nathan |journal=Journal of Environmental Studies and Sciences |volume=5 |issue=2 |pages=169–175 |bibcode=2015JEnSS...5..169Z |doi=10.1007/s13412-014-0215-7 |s2cid=128974741 |url=https://link.springer.com/article/10.1007%2Fs13412-014-0215-7}}
• {{cite journal |title=The role of HFCS in mitigating 21st century climate change |year=2013 |last1=Xu |first1=Y. |last2=Zaelke |first2=D. |last3=Velders |first3=G. J. M. |last4=Ramanathan |first4=V. |journal=Atmospheric Chemistry and Physics |volume=13 |issue=12 |pages=6083–6089 |bibcode=2013ACP....13.6083X |doi=10.5194/acp-13-6083-2013 |doi-access=free |url=https://acp.copernicus.org/articles/13/6083/2013/acp-13-6083-2013.html}}
• {{cite journal |title=Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in CO2 emissions |year=2009 |last1=Molina |first1=M. |last2=Zaelke |first2=D. |last3=Sarma |first3=K. M. |last4=Andersen |first4=S. O. |last5=Ramanathan |first5=V. |last6=Kaniaru |first6=D. |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=49 |pages=20616–20621 |pmid=19822751 |doi=10.1073/pnas.0902568106 |doi-access=free |pmc=2791591 |s2cid=13240115}}
• {{cite book |last1=Anderson |first1=S. O. |last2=Sarma |first2=M. K. |last3=Taddonio |first3=K. |year=2007 |title=Technology Transfer for the Ozone Layer: Lessons for Climate Change |location=London |publisher=Earthscan |isbn=9781849772846 |url=https://books.google.com/books?id=OvgA-hZrPOcC}}
• {{cite book |last1=Benedick |first1=Richard Elliot |author2=World Wildlife Fund (U.S.) |author3=Institute for the Study of Diplomacy. Georgetown University. |title=Ozone Diplomacy: New Directions in Safeguarding the Planet |edition=2nd |year=1998 |publisher=Harvard University Press |isbn=978-0-674-65003-9 |url=https://books.google.com/books?id=4yM9uPRUvi4C}} (Ambassador Benedick was the Chief U.S. Negotiator at the meetings that resulted in the Montreal Protocol.)
• {{cite book |last1=Chasek |first1=P. S. |last2=Downie |first2=David L. |last3=Brown |first3=J. W. |year=2013 |title=Global Environmental Politics |edition=6th |location=Boulder |publisher=Westview Press |isbn=9780813348971 |url=https://books.google.com/books?id=Ju41zgEACAAJ}}
• {{cite book |last=Grundmann |first=Reiner |title=Transnational Environmental Policy: Reconstructing Ozone |year=2001 |publisher=Psychology Press |isbn=978-0-415-22423-9 |url=https://books.google.com/books?id=FYyVDlRhBvEC}}
• {{cite book |last=Parson |first=E. |year=2003 |title=Protecting the Ozone Layer: Science and Strategy |location=Oxford |publisher=Oxford University Press |isbn=9780190288716 |url=https://books.google.com/books?id=VNkJCAAAQBAJ}}

{{Commons category|Ozone layer}}

{{Wikisource}}

• [http://www.ccpo.odu.edu/SEES/ozone/oz_class.htm Stratospheric ozone: an electronic textbook]
• [https://archive.today/20040702045343/http://www.unep.org/ozone/Public_Information/4Aii_PublicInfo_Facts_OzoneLayer.asp Ozone Layer Info] (archived July 2, 2004)
• The [http://www.copernicus-stratosphere.eu/ CAMS stratospheric ozone service] delivers maps, datasets, and validation reports about the past and current state of the ozone layer.

{{Earth's atmosphere}}

{{Authority control}}

Layer

Category:Ultraviolet radiation