The Ozone layer is changing

Ozone is located in the stratosphere and its role is to absorb harmful ultraviolet radiation from the sun and protect life on Earth. In recent years, people are constantly damaging the ozone layer, releasing harmful substances into the atmosphere which destroys ozone and disrupts the balance established by nature. Ozone (O3) is a form of elemental oxygen and is generated in the stratosphere as a result of the reaction between the molecules of oxygen and sunlight in a process called photolysis. 1. Photolysis of oxygen O2 + UV  2O 2. Synthesis of ozone 2О + 2О2  2O3

Solar ultraviolet radiation continuously produces new ozone albeit these ozone molecules are constantly destroyed in a sequence of catalytic reactions of compounds containing oxygen, nitrogen, hydrogen, chlorine and bromine. These substances come from the soil and oceans and pollute the atmosphere even before humans began to pollute. Because the process of photolysis releases heat, stratospheric temperature rises.

What is the state of the global ozone layer today What is the state of the global ozone layer today? At the time being, is more than clear that global ozone level is significantly lower than it was claimed in the past. Various human activities indicate a threat to the ozone layer, such as: 1. substances used in refrigerators and sprays (chlorofluorocarbon-CFC). These are gases that are not soluble in water and which by becoming diffused through the airflow are transported into the stratosphere. CFC in the stratosphere absorb high-energy photons which convey free chlorine that destroys ozone in a series of catalytic reactions. These reactions take place at extremely low temperatures (-80C).

2. Bromine fluorocarbon bromide, used for extinguishing fires can also be released into the stratosphere. Compared to chlorine it has 30 times the capacity of destroying ozone.   3. Halogen derivatives of hydrocarbons which instead fluorine and chlorine contain another halogen can survive more than a hundred years in the stratosphere, and thus destroy ozone.   4. N2O is released from supersonic aircraft flying in low parts of the stratosphere, nitrogen oxides produced by vehicles, power plants and industrial combustion processes are also a threat to the ozone.

Destruction of ozone in reaction to CFC and UV radiation Destruction of ozone in reaction to CFC and UV radiation CCl3F – UV = Cl- CCl2F Cl + O3  ClO + O2 O3 + UV  O2 + O O + ClO  Cl + O2 2O3  3O2 Destruction of the ozone reaction nitrogen monoxide (NO) as a catalyst and UV radiation NO - O3 = NO2 – O2 O3 + UV  O2 + O NO2 + O  NO + O2 2O3  3O2

However, the destruction of ozone over the Arctic is not that severe for two reasons: the temperature of the stratosphere rarely reaches values ​​below -80 ° C due to the regular ample change of air masses from the high latitudes; airflow over the Arctic ceases before the end of winter before the sun light triggers processes over Antarctica. Since 1970, the total ozone tends to decline everywhere except above the equator on a global scale (the ozone layer today looks like an old shabby cloth). If the equatorial belt where there are no significant ozone changes is excluded, ozone decline over middle and polar latitudes in the period of 1984-1993 compared to 1964 is more than 2 times. On the contrary, in the troposphere concentrations of ozone in the northern mid-latitudes in the last 100 years rose by more than 2 times and the tendency of growing further. This ozone cannot compensate for losses in the stratosphere. Unlike stratospheric ozone, which has a positive role to filter UV radiation, troposphere ozone, although chemically identical, has very different destructive properties. It is highly reactive with other molecules and its high concentrations are toxic to the living things and damages their tissues.

Cosmic radiation is involved in creating NO (cosmic rays entering the poles are almost parallel to the magnetic field lines). Spatial division during the formation of NO indicates that the Earth's magnetic field has an indirect impact on the concentration of NO, and therefore ozone. Studies show that NO production is the highest at the poles, therefore the ozone holes can be found right there. The large amounts of reactive chlorine and bromine present contributes to the destruction of ozone. Ozone is created year-round in the stratosphere over the equatorial belt. Through the air currents it is transported to polar latitudes. The loss of ozone is especially significant over Antarctica. The polar stratospheric clouds that attract water vapor and absorb nitrogen compounds contribute to that loss. With the advent of so-called Antarctic spring in September (the appearance of the sun and UV rays), stable reservoirs change into active types of chlorine and bromine on the surface of polar stratospheric clouds and destroy ozone very efficiently. The results are: loss of more than 40% of the ozone during the period of September and October (when the polar vortex of strong western winds carry ozone) and the biggest ever ozone hole area of ​​24 million km2.

Consequences of ozone depletion   Ozone affects the balance of receiving and driving back the heat from the Earth's atmosphere system with unpredictable consequences. Ozone reflects infrared radiation which is reissued from the Earth and goes back to her, helping in heating the lower layers (greenhouse). Thus the increase of ozone in the troposphere, particularly near the tropopause is causing warming, while reducing of the stratospheric ozone causes cooling. As ozone strongly absorbs UV-radiation from the solar spectrum with wavelengths shorter than 280 nm allows only a small part of it to reach the Earth's surface. The destruction of the ozone causes increased levels of UV-B radiation on the Earth's surface that has huge negative consequences on wildlife: skin cancer, eye cataracts (opacity of the eye lens), DNA damage, reducing the efficiency of the immune system, damage of some ecosystems, especially marine phytoplankton which is a major drain of CO2 and severe consequences as a result of climate change.  

What can be done to protect the ozone layer What can be done to protect the ozone layer? The concern about the destruction of the ozone layer firstly engages scientists and experts, and then secular organizations. To find a way out of this situation the Governmental Council of UNEP- United National Environmental Program - environmental organizations of the United Nations established the foundations of the ozone layer endangered in 1977. In 1985 the Vienna Convention obliged states to protect human health and the environment and to prepare effective measures. With the Montreal Protocol in 1987 actual measures were established which required CFC to be decreased to 20 % by the end of 1994, or about 50% by 1998. Despite such measures, it is difficult to predict when the ozone layer will be recovered and returned to its original condition. For contributions in elucidating the chemical reactions destroying ozone Nobel Prize in Chemistry in 1995 was divided between Paul Crutzene (1933) from the Max Planck Institute, Mario J. Moina (1943) of Massachusetts Institute of Technology and F. Sherwood Rowlend (1927) California University.