Montreal Protocol has helped to reduce 97 percent of global consumption and production of ozone depleting substances
For last 450 million years, earth has had a natural sunscreen in the stratosphere in form of Ozone (O3) layer. O3 is a highly reactive gas whose molecules are comprised of three oxygen atoms. Its concentration in the atmosphere naturally fluctuates depending on seasons and latitudes. This layer filters out the harmful ultraviolent radiations from the sun and thus protects various forms of life on earth.
The theory about the ozone depletion was first given in1974 by American scientists Mario Molina and F Sherwood Rowland. Ozone depletion refers to the thinning of the ozone layer in the stratosphere. The concentration is greater in the lower stratosphere, (15 to 35 km), and this ozone layer is called good ozone due to its protective role for living organisms including humans by filtering out about 95 percent of harmful radiations. Only 10 percent of ozone found near the ground in the troposphere is harmful pollutant as a component of urban smog and thus is called bad ozone.
In the stratosphere, the formation and destruction of ozone is a combination phenomenon, because the rate of formation is equal to the rate of destruction by natural processes. Man- made chemicals that are Ozone Depleting Substances (ODS) are Chlorofluorocarbons (CFCs), nitrogen oxides, sulphur dioxide, carbon tetra chloride, methyl chloroform, chlorine etc. Many of these gases are being released by flying jets in stratosphere and rockets being fired into space. Also, other gases are persistent into the troposphere and gradually pass into the stratosphere.
Maximum Ozone Depleting Potential (ODP) is due to release of active chlorine as it gets perched over the atmospheric ice crystals and remains functional for a long time. Consequently, CFCs are being replaced by Hydrofluorocarbons (HCFs) and Hydrochlorofluorocarbons (HCFCs). Also, the gases with longer lifetimes have slower conversion rates and survive longer in the atmosphere after emission. Meanwhile, the lifetime of principles, ODSs vary from 1 to 100 years. The radicals formed from ODSs react chemically to destroy ozone in the stratosphere.
The UV rays are of three types: UV-C (100-280), UV-B (280-320) and UV-A (320-390). Shorter Ultra Violent Radiations (UV-C) are absorbed by the atmosphere. UV-B is harmful as well as capable of deep penetration. Vice versa, it has ill effects on human health like sunburns, eye cataracts, immune system suppression or skin cancer etc; Forests and Wildlife: decrease in forest productivity, aquatic species, disrupted food webs etc; Air Pollution and Materials: increased acid and photochemical smog production, degradation of outdoor paints and plastics; and finally Global Warming: there can be possible climate changes due to accelerated warming.
Ozone hole over Antarctica has a total ozone layer of 220 Dobson Units or lower as the ozone depleting substances released by humans globally reach the stratosphere from where they are pushed over poles by winds.
During winters, there is no sunlight and thus the temperature over Antarctica is low like -85 degree Celsius. The winters favours formation of ice clouds and these ice clouds provide catalytic surface where chlorine and other reactants of ODS can react with ozone and degrade it. Ozone hole disappears during summer as warmth mixes up in the Antarctic air with air of other parts of the world.
In 1985, countries adopted the Vienna Convention for protection of ozone layer and two years later, Montreal Protocol was adopted. Till date, the Montreal Protocol has helped to reduce the 97 percent of global consumption and production of ozone depleting substances.
The question is how to protect ozone layer 1?
Avoid consumption of dangerous gases
We should avoid the consumption of dangerous gases like CFCs, halogenated hydrocarbon, methyl bromide and nitrous oxide. We should stop their use all together.
Minimize use of cars
The best transport option bicycle, or walking. If you use a car, try to carpool with others to decrease the use of cars in order to pollute less and save.
Stop using cleaning products
Many cleaning products contain solvents and substances corrosive. We can replace these dangerous substances with non-toxic products such as vinegar or bicarbonate.
Buy local products
By buying local products we not only get fresh products but we also avoid consuming food that has travelled long distances. As the more distance travelled, the more nitrous oxide is produced due to the medium used to transport the product.
Maintain air conditioners
We should maintain our air conditioners as their malfunctions cause CFCs to escape into the atmosphere.
In January 2019, some amendments were made to the protocols to slash the use HFCs by more than 80 percent over the next three decades. In the meantime, companies and scientists are working on climate friendly alternatives, including new coolants and technologies that can reduce or eliminate dependence on chemicals. We need to protect the ozone from depletion and we can only achieve it once the world unites and decides to work together.