What is the ozone layer and why is its destruction harmful to us?
What is the ozone layer and why is its destruction harmful to us?
- The ozone layer is a layer in the upper layers of the stratosphere containing O3 ozone, which, thanks to its unique properties, protects the earth and all living things on it from the harmful effects of ultraviolet radiation coming from the sun. If there was not this layer, we would not be able to sunbathe you in the sun, but would turn into a "boiled sausage". In short, there would not be us)))
Substances contained in gas cartridges and freons from refrigerators, volatilizing, destroy this layer. Therefore, there are "ozone holes" - the area above the Earth, where there is little ozone. This is alarming environmental scientists for more than a decade.
- Ozo # 769, the new layer is part of the stratosphere at an altitude from 12 to 50 km, where oxygen (O2) ionizes under the influence of ultraviolet solar radiation, acquiring the third oxygen atom, and ozone (O3) is produced. The relatively high concentration of ozone (about 8 ml / m # 179;) absorbs dangerous ultraviolet rays and protects all living on land from harmful radiation. Moreover, if it were not for the ozone layer, life would not be able to get out altogether from the 1 oceans and highly developed forms of life such as mammals, including humans, would not have arisen. The highest density of ozone occurs at an altitude of about 20-25 km, the largest part in the total volume at an altitude of 40 km. If it were possible to extract all the ozone in the atmosphere and compress under normal pressure, the result would be a layer covering the Earth's surface with a thickness of only 3 mm. For comparison, all compressed under normal pressure atmosphere would be a layer at 8 km.
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- 20-50 km above the Earth's surface in the atmosphere is a layer of ozone. (Ozone is a special form of oxygen). The ozone layer of the atmosphere is very thin. If all available ozone in the atmosphere is evenly covered by an area of 45 square kilometers, then a layer with a thickness of only 0,3 cm will be obtained. A little ozone penetrates with air currents into the lower layers of the atmosphere. When the light rays react with substances contained in exhaust gases and industrial emissions, the result of photochemical reactions is the so-called ground-level ozone. Usually such a situation develops in large cities with an anticyclone type of weather. Breathing with such ozone is very dangerous, since this gas destroys the lungs. Pedestrians, inhaling a large amount of ozone, begin to choke, feel pain in the chest. There are also trees and bushes growing along the gassy roads. But if ozone is located where it should be at high altitude, then it is very useful for health. Ozone absorbs ultraviolet rays, which in large doses can cause sunburn and even skin cancer. About the ozone layer, the in-depth information was learned in the 70-s of the last century. At the same time, it was discovered that chlorofluorocarbon derivatives (freons) used in refrigerators, air conditioners, aerosol cans - destroy ozone. Rising to the upper layers of the atmosphere, the molecules of freons interact with molecules of ozone. Under the influence of solar radiation freons produce chlorine, which splits ozone with the formation of ordinary oxygen. In the place of such interaction, the ozone layer disappears. In 1985 the British scientists made an opening. They discovered over Antarctica a huge hole in the ozone layer the size of the US area. As it turned out, in the sky over Antarctica, the concentration of chloric acid anhydride is high, the compound formed at the time of the destruction of the ozone molecule by chlorine. This is confirmed by the fact that the use of freons will create a problem of ozone holes. That is why in 1985 representatives of 44 States adopted the Convention on the Protection of the Ozone Layer, and in 1986, the Montreal Protocol was signed to limit the production and consumption of ozone-depleting substances. Of course, the ozone hole does not exist constantly - with a number of factors it is filled with ozone molecules from a number of located areas of the atmosphere, but the amount of ozone in neighboring areas is significantly reduced. Uchnye calculated that a decrease in ozone in the upper layers of the atmosphere by 1% causes an increase in the incidence of skin cancer by 3-6%. UV rays have a damaging effect on the body's immune system, making us more susceptible to infectious diseases, and also destroy plant cells. In addition, depletion of the ozone layer can unpredictably change the Earth's climate. After all, the ozone layer delays heat that dissipates from the surface of the Earth. As the amount of ozone in the air T decreases, the direction of the prevailing winds changes and the weather changes. The analysis of total ozone data confirmed the trend of decreasing atmospheric ozone, noted in the reviews of the World Meteorological Organization in 1995. From 1979 year to the present, the annual ozone content decreased by 4-5% globally and by about 7% in the mid latitudes of both hemispheres. In recent decades, a significant decrease in ozone, previously observed mainly over Antarctica, has become noticeable in the Arctic regions and adjacent areas of the Northern Hemisphere. The research work carried out recently by Russian scientists has established that if in the period of 1979-1993 gg. there was a decrease in the average annual ozone content, then in the future the situation stabilized. In addition, with an increase in the amount of observations that allow more and more detailed description of the state of the ozone layer, new evidence appears that the changes are not only related to anthropogenic influences, but, to a large extent,
- Since the beginning of the 20 century, scientists have been monitoring the state of the ozone layer of the atmosphere. Now everyone understands that stratospheric ozone is a kind of natural filter that prevents penetration of hard cosmic radiation - ultraviolet-B - into the lower layers of the atmosphere.
16 September 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer was adopted. Subsequently, on the initiative of the UN, this day was celebrated as the Day of Protection of the Ozone Layer.
Since the end of 70-ies, scientists have begun to note the steady depletion of the ozone layer. The reason for this was the penetration of ozone-depleting substances (ODS) used in industry, molecules of which contain chlorine or bromine, into the upper layers of the stratosphere. Chlorofluorocarbons (CFCs) or other ODS released by humans into the atmosphere reach the stratosphere where, under the action of the short-wave ultraviolet radiation of the Sun, their molecules lose the chlorine atom. Aggressive chlorine begins to break one after another ozone molecules, while not undergoing any changes. The life of various CFCs in the atmosphere from 74 to 111 years. It has been calculated by calculation that during this time one chlorine atom is able to turn into oxygen 100 000 molecules of ozone.
According to doctors, each lost percentage of ozone on the scale of the planet causes up to 150 thousand additional cases of blindness due to cataracts, 2,6 percent increases the number of skin cancers, significantly increases the number of diseases caused by weakening of the human immune system. The inhabitants of the northern hemisphere with light skin are at greatest risk. But not only people are affected. UV-B radiation, for example, is extremely harmful to plankton, fry, shrimp, crabs, algae that live on the surface of the ocean.
The ozone problem, originally raised by scientists, soon became the subject of politics. All developed countries, with the exception of Eastern Europe and the former USSR, by the end of 1995 basically completed a phased reduction in the production and consumption of ozone-depleting substances. To help other countries, the Global Environment Facility (GEF) was established.
According to the UN, thanks to the concerted efforts of the world community undertaken in the last decade, production of the five main types of CFCs has more than halved. The rate of growth of ozone-depleting substances in the atmosphere has decreased.
Location and functions of the ozone layer
Ozone is always present in the air, the concentration of which on the earth's surface is on the average 10-6%. Ozone is formed in the upper atmosphere from atomic oxygen as a result of a chemical reaction under the influence of solar radiation, which causes the dissociation of oxygen molecules.
The ozone screen is located in the stratosphere, at altitudes of7-8 km at the poles, 17-18 kilometers at the equator and about 50 kilometers above the earth's surface. The most common ozone in the 22 layer is 24 kilometers above the Earth.
The ozone layer is surprisingly thin. If this gas were concentrated near the surface of the Earth, then it would form a film only in 2-4 mm thick (minimum - near the equator, maximum at the poles). However, this film also protects us, almost completely absorbing dangerous ultraviolet rays. Without it, life would be preserved only in the depths of the water (deeper than 10 m) and in those layers of soil where solar radiation does not penetrate. Ozone absorbs some of the infrared radiation of the Earth. Due to this, it detains about 20% of the Earth's radiation, increasing the heating effect of the atmosphere.
Ozone is an active gas and can adversely affect a person. Usually its concentration in the lower atmosphere is insignificant and it does not have a harmful effect on a person. Large amounts of ozone are formed in large cities with heavy traffic as a result of photochemical transformations of car exhaust gases.
- The ozone layer as a protective screen protects our planet from direct sunlight (solar energy), carbon dioxide, which escapes into the atmosphere (pollution of the planet, etc.) -increases (depletes), destroys the ozone layer, creates holes in the ozone layer, from this the climate on the planet is changing, glaciers are melting ...
- The oxygen molecule (which in the air is contained and to which we breathe) consists of two atoms.
If ultraviolet radiation hits the molecules of oxygen, then they "cling" to themselves the third atom - an ozone molecule is produced.
And since the energy of ultraviolet radiation has gone into the formation of a new molecule, then this radiation (very harmful) does not reach the earth.
That is, ozone (not ozone itself, but its formation) protects us from the harsh ultraviolet that causes skin cancer and in general a nasty thing.
PS its destruction to us, it turns out, somehow on the side
- The ozone layer is part of the stratosphere at an altitude from 12 to 50 km, in which oxygen (O2) is ionized by the ultraviolet radiation of the Sun, acquiring the third oxygen atom, and ozone (O3) is produced. The relatively high concentration of ozone (about 8 ml / m) absorbs dangerous ultraviolet rays and protects all living on land from harmful radiation. Moreover, if it were not for the ozone layer, life would not be able to get out altogether from the 1 oceans and highly developed forms of life such as mammals, including humans, would not have arisen. The highest density of ozone occurs at an altitude of about 20-25 km, the largest part in the total volume at an altitude of 40 km. If it were possible to extract all the ozone in the atmosphere and compress under normal pressure, the result would be a layer covering the Earth's surface with a thickness of only 3 mm. For comparison, all compressed under normal pressure atmosphere would be a layer at 8 km.