Atmospheric ozone has a specific persistence and lifetime before chemical destruction
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Retrieved literature confirms that atmospheric ozone is continuously formed, maintained, and chemically destroyed through specific atmospheric reactions.
This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595-828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.
2.2 ) are consistent with the decrease in the concentration of ODSs regulated by the Montreal Protocol. Assuming continued adherence to the Montreal Protocol, concentrations of ODSs are projected to decline further, eventually resulting in the disappearance of the annually recurring ozone hole in the second half of the twenty-first century [ 7 ]. Until that time, large year-to-year variations in the various ozone hole metrics are expected because of the sensitivity of chemical ozone destruction to temperatures in the lower stratosphere in the presence of ODSs as explained below.
The average TOC in 2020 for this 3-month period was 340 DU, which is 100 DU below the mean of measurements between 1979 and 2019 and the lowest value since the start of satellite measurements in 1979. The low TOCs in 2020 were partially caused by a strong and long-lived polar vortex, which provided ideal conditions for chemical ozone destruction to take place. Temperatures low enough to form PSCs within the vortex developed early in the season, and on average enclosed about a third of the vortex volume [ 54 – 58 ]. These conditions are unique in the ~ 40 years of measurements, making 2020 the year with the largest Arctic ozone loss on record.
The largest effects on incidence of skin cancer are estimated to occur in people born between 1960 and 1980 since these birth cohorts experienced the full period of stratospheric ozone depletion, and will also have received the largest cumulative lifetime dose of UV radiation. The model estimates that cohorts born in 2040 or later will not experience any excess incidence of skin cancer caused by the effects of ozone depletion.
The undesirable photochemical conversion of macroplastics to micro- and nano-plastics also may have been lessened by the actions of the Montreal Protocol. Specific examples are provided of relationships between biogeochemical cycles and the SDGs 3, 6, 12, 13, 14, and 15, with an emphasis on carbon and nitrogen cycling in terrestrial and aquatic systems, and the cryosphere; as well as on chemical and biological contaminants.
It is also influenced by atmospheric circulation, including transport of ozone from the stratosphere to the troposphere, which can be altered by changes in climate and as a result of ODS [ 37 ]. Understanding how air quality depends on changes in UV radiation, whether from depletion of ozone or other causes (e.g., aerosols), remains a fundamental challenge to the prediction of air quality. The hydroxyl radical (OH) is the major oxidant of tropospheric pollutants and is central to the regulation of ambient air quality. OH is primarily produced by the absorption of UV-B radiation by ozone (Fig. 12 ) and the concentration of OH determines the persistence of many pollutants in the atmosphere.
OH is usually destroyed when it reacts with pollutants, so that the actual concentration of OH is a balance between UV-B-driven production and its reaction with pollutants. Climate change may enhance the emission of tropospheric pollutants, like CO, from natural sources and this would reduce the concentration of OH and increase the persistence of other chemicals, including the greenhouse gas (GHG), methane (CH 4 ), and very short-lived halogen compounds (VSLS), such as bromoform (CHBr 3 ) that could increase destruction of stratospheric ozone and change concentrations of tropospheric ozone [ 359 ] (Fig. 12 ).
The effect of UV radiation on the atmospheric chemistry and lifetime of aerosols is larger than previously recognised It is well established that UV radiation is central to the formation of many aerosols in the atmosphere, such as those containing sulfate, nitrate, and many organic compounds. These so-called secondary organic aerosols (SOA) are formed in the atmosphere through the oxidation of VOCs that form low volatility products (Fig. 12 ). New research indicates that UV radiation also plays a role in the destruction of some of these particles.
No attempt has yet been made to quantify the sensitivity of the lifetimes of different SOA to changes in UV radiation as would occur with changes in stratospheric ozone. UV radiation induces chemical transformations on the surface of and within aerosol particles, producing chemical species potentially damaging to air quality and health Heterogeneous photochemistry of aerosol particles has attracted increasing interest in the past decade due to its potential to modify the chemical composition, toxicity, and optical properties of aerosols [e.g., [ 370 , 371 ]].
This requires reliable laboratory-accelerated weathering procedures that estimate durability under specific exposure conditions as well as good lifetime models that yield good estimates of service lifetimes from weathering data [ 492 ]. However, acceleration of photo-damage in the laboratory has to ensure that wavelengths and
Volcanic super-eruptions can perturb atmospheric composition and climate-relevant radiative properties in ways that are not captured by simple scaling from Pinatubo-like events. This study presents a reduced-order regime theory for the coupled evolution of stratospheric sulfur, sulfate aerosol burden, reactive halogens, ozone loss, stratospheric thermal adjustment, and aerosol residence time. The analysis is intended as an interpretive tool for organizing sulfur-rich volcanic scenarios, comparing literature-based benchmark classes, and designing chemistry–climate model experiments, rather than as an event-specific calibration or a substitute for three-dimensional models. Four control parameters structure the response: sulfur loading relative to microphysical saturation, effective halogen strength, ash-uptake efficiency, and dynamical lifetime sensitivity, with hemispheric asymmetry treated diagnostically. An external consistency check against published Pinatubo-like, idealized 10–40 teragrams of sulfur (Tg S), Toba-like, and Los Chocoyos-like responses is used to evaluate whether the reduced theory reproduces the expected rank ordering of aerosol saturation, forcing-efficiency decline, ozone-loss amplification, ash-driven sulfur suppression, and residence-time sensitivity. This comparison does not assign pointwise error margins against three-dimensional model output; it evaluates regime membership, sign of response, rank ordering, and broad magnitude behavior. The main conclu
The concentrations of trace gases in the atmosphere have changed over time and so have the chemical processes which make and destroy compounds in the air. Two important examples of this were the explanation by Sydney Chapman and Gordon Dobson of how the ozone layer is created and maintained, and the explanation of photochemical smog by Arie Jan Haagen-Smit. Further studies on ozone issues led to the 1995 Nobel Prize in Chemistry award shared between Paul Crutzen, Mario Molina and Frank Sherwood Rowland.[2]
In the 21st century the focus is now shifting again. Atmospheric chemistry is increasingly studied as one part of the Earth system. Before, scientists focused on atmospheric chemistry in isolation. Now, scientists study atmospheric chemistry as one part of a single system with the rest of the atmosphere, biosphere and geosphere. A reason for this is the links between chemistry and climate. For example, changing climate and the recovery of the ozone hole affect each other. Also, the composition of the atmosphere interact with the oceans and terrestrial ecosystems. Methodology
Observations, lab measurements and modeling are the three central elements in atmospheric chemistry.
Atmospheric chemistry is a branch of atmospheric science that studies the chemistry of the Earth's atmosphere and that of other planets. This multidisciplinary approach of research draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology, climatology and other disciplines to understand both natural and human-induced changes in atmospheric composition. Key areas of research include the behavior of trace gasses, the formation of pollutants, and the role of aerosols and greenhouse gasses. Through a combination of observations, laboratory experiments, and computer modeling, atmospheric chemists investigate the causes and consequences of atmospheric changes.
The first scientific studies of atmospheric composition began in the 18th century when chemists such as Joseph Priestley, Antoine Lavoisier and Henry Cavendish made the first measurements of the composition of the atmosphere.
In the late 19th and early 20th centuries, researchers shifted their interest towards trace constituents with very low concentrations. An important finding from this era was the discovery of ozone by Christian Friedrich Schönbein in 1840.
In the 20th century atmospheric science moved from studying the composition of air to consider how the concentrations of trace gasses in the atmosphere have changed over time and the chemical processes which create and destroy compounds in the air. Two important outcomes were the explanation by Sydney Chapman and Gordon Dobson of how the ozone layer is created and maintained, and Arie Jan Haagen-Smit’s explanation of photochemical smog. Further studies on ozone issues led to the 1995 Nobel Prize in Chemistry award shared between Paul Crutzen, Mario Molina and Frank Sherwood Rowland.
In the 21st century the focus is now shifting again. Instead of concentrating on atmospheric chemistry in isolation, it is now seen as one part of the Earth system with the rest of the atmosphere, biosphere and geosphere. A driving force for this link is the relationship between chemistry and climate. The changing climate and the recovery of the ozone hole and the interaction of the composition of the atmosphere with the oceans and terrestrial ecosystems are examples of the interdependent relationships between Earth's systems. A new field of extraterrestrial atmospheric chemistry has also recently emerged. Astrochemists analyze the atmospheric compositions of the Solar System and exoplanets to determine the formation of astronomical objects and find habitual conditions for Earth-like life.
- UV + O2 -> 2O + heat, O2 + O -> O3, O3 + O -> 2O2
- Which reactions demonstrate the destruction of the ozone layer? - Cl + O3 ------> ClO + O2 and ClO + O ------> Cl + O
- How do CFC's destroy the ozone layer? - the atomic chlorine freed from CFC reacts in a catalytic manner with ozone and atomic oxygen to make more oxygen molecules
- Why should regulations be enforced now in regards to pollution and harmful chemicals? - without regulation, the production and use of chemicals will run out of hand and do irreversible damage to the stratosphere
- What type of atom in the CFC molecule is most destructive to the ozone? - chlorine
- In which layer of the atmosphere does the ozone layer? - the stratosphere, the second closest to the Earth's surface
- What cycle is responsible for ozone in the stratosphere? - the Chapman cycle
- What factor is responsible for breaking up stable molecules? - ultraviolet rays from the sun
Ozone is an elemental molecule with formula O3. An explosive, pale blue gas (b.p. 112C) that has a characteristic, pungent odour, it is continuously produced in the upper atmosphere by the action of solar ultraviolet radiation on atmospheric oxygen. It is an antimicrobial agent used in the production of bottled water, as well as in the treatment of meat, poultry and other foodstuffs. It has a role as a mutagen, a tracer, an antiseptic drug, a disinfectant, an electrophilic reagent, an oxidising agent and a member of greenhouse gas. It is a gas molecular entity, an elemental molecule, a member
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