Ozone layer hole (Ozonosphere hole) The ozone content in the atmosphere is only one part per 100 million, but there is an ozone layer in the stratosphere 20 to 30 kilometers above the ground, and the ozone content accounts for 100,000 parts of the total air at this altitude.
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Although the ozone content of the ozone layer is extremely small, it has a very strong ability to absorb ultraviolet rays and can absorb the biologically harmful part of the ultraviolet rays of sunlight (UV-B).
Because the ozone layer effectively blocks the invasion of ultraviolet rays from the sun, humans and all kinds of life on earth can exist, reproduce and develop.
In 1985, British scientists observed the ozone layer hole over Antarctica and confirmed that it was directly related to the chlorine atoms produced by the decomposition of Freon (CFCs).
The news shocked the world.
By 1994, the area of ??ozone destruction over Antarctica had reached 24 million square kilometers, and the ozone layer over the Northern Hemisphere was thinner than ever before. The ozone layer over Europe and North America had decreased by an average of 10%-15%, and even decreased by 35% over Siberia.
%. Scientists warn that the degree of destruction of the ozone layer on the earth is much more serious than most people imagine. Ozone-depleting substances such as Freon are the culprits of the destruction of the ozone layer. Freon was synthesized in the 20s of this century and has stable chemical properties.
Due to its flammability and toxicity, it is used as a refrigerant, foaming agent and cleaning agent, and is widely used in household appliances, foam plastics, daily chemicals, automobiles, fire-fighting equipment and other fields. In the late 1980s, the production of Freon reached its peak.
Production reached 1.44 million tons. Before the control of Freon, the world's emissions of Freon into the atmosphere reached 20 million tons. Since their average lifespan in the atmosphere is hundreds of years, most of the emissions remain.
In the atmosphere, most of them still stay in the troposphere, and a small part rises into the stratosphere. Freon, which is quite stable in the troposphere, will be decomposed under certain meteorological conditions under the action of strong ultraviolet light.
The chlorine atoms released by decomposition will have a chain reaction with ozone, continuously destroying ozone molecules. Scientists estimate that one chlorine atom can destroy tens of thousands of ozone molecules. Freon and other ozone-depleting substances are the culprits of the destruction of the ozone layer. Freon was synthesized in the 1920s.
, its chemical properties are stable, non-flammable and toxic, and is used as a refrigerant, foaming agent and cleaning agent. It was widely used in household appliances, foam plastics, daily chemicals, automobiles, fire-fighting equipment and other fields in the late 1980s.
, the production of Freon reached its peak, with output reaching 1.44 million tons. Before the control of Freon, the world's emissions of Freon into the atmosphere reached 20 million tons. Because their average lifespan in the atmosphere is hundreds of years.
Therefore, most of the emissions remain in the atmosphere, most of which still stay in the troposphere, and a small part rises into the stratosphere. After rising into the stratosphere, under certain meteorological conditions, Freon will remain in the stratosphere.
It is decomposed under the action of strong ultraviolet rays, and the chlorine atoms released by the decomposition will have a chain reaction with ozone, continuously destroying ozone molecules. Scientists estimate that one chlorine atom can destroy tens of thousands of ozone molecules. Ways and policies to control the destruction of the ozone layer in the modern economy.
, Freon and other substances are widely used. To completely eliminate them, we must first find alternative substances and alternative technologies for Freon and other substances. In special cases, efforts should also be made to recycle and reuse as much as possible. Currently, some of the world's major production of Freon.
Manufacturers have participated in the development and research of fluorine-containing alternatives to Freon (hydrochlorofluorocarbons, HCFCs, hydrofluoroalkanes, HCF, etc.) and their synthesis methods. They may be used as foaming agents, refrigerants, cleaning solvents, etc., but this type of
Substitutes also damage the ozone layer or produce a greenhouse effect. At the same time, non-Freon type alternative substances and methods are also being developed and researched, such as water cleaning technology, ammonia refrigeration technology, etc., in order to promote the development and use of Freon alternative substances and technologies and gradually phase out the ozone layer depletion.
Regarding substances, many countries have adopted a series of policy measures. One is traditional environmental control measures, such as bans, restrictions, quotas and technical standards, and the implementation of severe penalties for violations.
EU countries and some countries with economies in transition have widely adopted such measures.
One category is economic means, such as levying taxes and fees, funding the development of alternative materials and technologies, etc.
The United States has implemented measures such as taxes and tradable licenses on the production and use of ozone-depleting substances.
In addition, governments, enterprises and civil society groups in many countries have also launched voluntary actions to adopt various environmental labels to encourage producers and consumers to produce and use materials and products that do not contain ozone-depleting substances. Among them, the green refrigerator label has been very popular.
Wide range of applications.
In 1985, with the promotion of the United Nations Environment Program, the Vienna Convention to protect the ozone layer was formulated.
In 1987, the United Nations Environment Program organized the formulation of the Montreal Protocol on Substances that Deplete the Ozone Layer, which set forth time requirements for reducing the use of eight substances that deplete the ozone layer (referred to as controlled substances).
The protocol has been ratified by 163 countries.