How is ozone destroyed naturally

CFCs rise and gradually accumulate in the stratosphere where they are broken down by the sun's ultraviolet light, so releasing chlorine atoms. The chlorine attacks the ozone, one chlorine atom can help to destroy , ozone molecules. The Montreal Protocol banning CFCs was signed by leading industrial nations in though the ozone layer continued to thin for the next decade as countries sought to reduce their use. As reported in The Independent in 'China raised its emissions from 29, tons in to 51, in ; South Korea from 8, to 9, tons and the Philippines from 1, to 2, tons'.

But ozone makes up only one to ten out of every million molecules in the ozone layer. The rest of the molecules are mostly nitrogen and oxygen, like the air we breathe.

There isn't much of it, but ozone is powerful, able to block the most harmful radiation. Ozone absorbs the most energetic wavelengths of ultraviolet light , known as UV-C and UV-B, wavelengths that harm living things. Oxygen molecules absorb other forms of ultraviolet light, too. Together, ozone and oxygen molecules are able to absorb 95 to When UV light is absorbed by oxygen and ozone, heat is generated, which is why the stratosphere gets warmer with altitude.

The ozone layer in the stratosphere shields life on Earth from most UV-B and UV-C, the most harmful varieties of ultraviolet radiation. Credit: NASA. Ozone and oxygen molecules are constantly being formed, destroyed, and reformed in the ozone layer as they are bombarded by ultraviolet radiation UV , which breaks the bonds between atoms, creating free oxygen atoms.

Free oxygen atoms are highly reactive, meaning that they bond easily with other molecules. If a free oxygen atom bumps into an oxygen molecule O 2 , it will form ozone O 3. As they reach the stratosphere, the sun's UV rays break CFCs down into substances that include chlorine. One atom of chlorine can destroy more than , ozone molecules, according to the U. Environmental Protection Agency, eradicating ozone much more quickly than it can be replaced.

The "hole" is actually an area of the stratosphere with extremely low concentrations of ozone that reoccurs every year at the beginning of the Southern Hemisphere spring August to October. Spring brings sunlight, which releases chlorine into the stratospheric clouds. Recognition of the harmful effects of CFCs and other ozone-depleting substances led to the Montreal Protocol on Substances That Deplete the Ozone Layer in , a landmark agreement to phase out those substances that has been ratified by all UN member countries.

Without the pact, the U. More than 30 years after the Montreal Protocol, NASA scientists documented the first direct proof that Antarctic ozone is recovering because of the CFC phase-down: Ozone depletion in the region has declined 20 percent since And at the end of , the United Nations confirmed in a scientific assessment that the ozone layer is recovering, projecting that it would heal completely in the non-polar Northern Hemisphere by the s, followed by the Southern Hemisphere in the s and polar regions by A study in early found that ozone in the lower stratosphere unexpectedly and inexplicably has dropped since , while another pointed to possible ongoing violations of the Montreal pact.

The world is not yet in the clear when it comes to harmful gases from coolants. Some hydrochlorofluorocarbons HCFCs , transitional substitutes that are less damaging but still harmful to ozone, are still in use.

Developing countries need funding from the Montreal Protocol's Multilateral Fund to eliminate the most widely used of these, the refrigerant R The next generation of coolants, hydrofluorocarbons HFCs , do not deplete ozone, but they are powerful greenhouse gases that trap heat, contributing to climate change.

Though HFCs represent a small fraction of emissions compared with carbon dioxide and other greenhouse gases , their planet-warming effect prompted an addition to the Montreal Protocol, the Kigali Amendment , in The amendment, which came into force in January , aims to slash the use of HFCs by more than 80 percent over the next three decades. Solvent use ended when it was discovered to be carcinogenic. It is also used as a catalyst to deliver chlorine ions to certain processes.

Its ozone depletion potential is 1. Methyl chloroform is used as an industrial solvent. Its ozone depletion potential is 0.

ODS that release bromine include halons halons Compounds, also known as bromofluorocarbons, that contain bromine, fluorine, and carbon. They are generally used as fire extinguishing agents and cause ozone depletion. Bromine is many times more effective at destroying stratospheric ozone than chlorine. Methyl Bromide is an effective pesticide used to fumigate soil and many agricultural products. Because it contains bromine, it depletes stratospheric ozone and has an ozone depletion potential of 0.

Production of methyl bromide was phased out on December 31, , except for allowable exemptions. In the s, concerns about the effects of ozone-depleting substances ODS ODS A compound that contributes to stratospheric ozone depletion. Gaseous CFCs can deplete the ozone layer when they slowly rise into the stratosphere, are broken down by strong ultraviolet radiation, release chlorine atoms, and then react with ozone molecules.

See Ozone Depleting Substance. Aerosols are emitted naturally e. There is no connection between particulate aerosols and pressurized products also called aerosols. See below propellants. However, global production of CFCs and other ODS continued to grow rapidly as new uses were found for these chemicals in refrigeration, fire suppression, foam insulation, and other applications.

Some natural processes, such as large volcanic eruptions, can have an indirect effect on ozone levels. For example, Mt. Pinatubo's eruption did not increase stratospheric chlorine concentrations, but it did produce large amounts of tiny particles called aerosols aerosols Small particles or liquid droplets in the atmosphere that can absorb or reflect sunlight depending on their composition.

These aerosols increase chlorine's effectiveness at destroying ozone. The aerosols in the stratosphere create a surface on which CFC-based chlorine can destroy ozone. However, the effect from volcanoes is short-lived. Not all chlorine and bromine sources contribute to ozone layer depletion. For example, researchers have found that chlorine from swimming pools, industrial plants, sea salt, and volcanoes does not reach the stratosphere. In contrast, ODS are very stable and do not dissolve in rain.