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The hole in the ozone layer


The ozone layer is a "cover" This gas surrounds the Earth and protects it from various types of radiation, the main one being ultraviolet radiation, which is the main cause of skin cancer.

In the last century, due to industrial development, products emitting chlorofluorocarbon (CFC), a gas that upon reaching the ozone layer destroys the molecules that form it (O3), thus causing the destruction of this layer from the atmosphere. Without this layer, the incidence of earth-damaging ultraviolet rays increases significantly, increasing the chances of cancer contracting.

Ultraviolet rays they are lightwave-like waves that are just above the violet end of the visible light spectrum. The wavelength of ultraviolet rays ranges from 4.1 x 10-4 to 4.1 x 10-2 mm, with their shortest waves being the most harmful.

Mainly responsible for the hole in the ozone layer, CFCs (chlorofluorocarbons) - used as refrigerants and aerosol propellants - were outlawed by the 1987 Montreal Protocol, but can still remain in the atmosphere for many years.

The hole

The region most affected by the destruction of the ozone layer is the Antarctica. In this region, especially in September, almost half of the ozone concentration is mysteriously sucked from the atmosphere. This phenomenon leaves at the mercy of ultraviolet rays an area of ​​31 million square kilometers, larger than all of South America, or 15% of the planet's surface.

In other areas of the planet, the depletion of the ozone layer is also noticeable; 3 to 7% of its ozone has been destroyed by man. Even smaller than Antarctica, these numbers are a huge warning for what might happen to us if we continue to close our eyes to this problem.

The reaction

The chlorofluorocarbon molecules, or Freon, pass intact through the troposphere, which is the part of the atmosphere that goes from the surface to an average altitude of 10,000 meters. Then these molecules reach the stratosphere, where the ultraviolet rays of the sun appear in greater quantities. These rays break the CFC (ClFC) particles by releasing the chlorine atom. This atom then breaks down the ozone molecule (O3), forming chlorine monoxide (ClO) and oxygen (O2).

The reaction continues and soon the chlorine atom releases oxygen that binds to one oxygen atom of another ozone molecule, and the chlorine atom begins to destroy another ozone molecule, creating a chain reaction.

On the other hand, there is the reaction that benefits the ozone layer: When sunlight acts on nitrogen oxides, they can react by releasing the combining oxygen atoms that produce ozone.

These nitrogen oxides are continuously produced by motor vehicles as a result of burning fossil fuels.

Unfortunately, CFC production, even though it is lower than nitrogen oxides, can, due to the chain reaction already explained, destroy much more ozone molecules than those produced by automobiles.

Why in Antarctica?

Air masses circulate around the world, and a pollutant released in Brazil can reach Europe due to convection currents. In Antarctica, on the other hand, due to the harsh winter of six months, this air circulation does not occur and thus convection circles unique to that area are formed. Pollutants attracted during the summer remain in Antarctica until they reach the stratosphere. By summer, the first rays of the sun break the CFC molecules found in this area, initiating the reaction. In 1988 it was found that in the Antarctic atmosphere, chlorine monoxide concentration is 100 times higher than in any other part of the world.

In Brazil there is still little to worry about

In Brazil, the ozone layer has not yet lost 5% of its original size, according to INPE (Space Research Institute) measuring instruments. The institute has been monitoring the movement of gas in the atmosphere since 1978 and to date has not detected any significant variation, probably due to the low production of CFCs in Brazil compared to first world countries. In Brazil, only 5% of aerosols use CFCs, as a mixture of butane and propane is significantly cheaper and works perfectly in place of chlorofluorocarbon.

The Evils

The main consequence of ozone depletion will be the large increase in the incidence of skin cancer, since ultraviolet rays are mutagenic. In addition, there is a hypothesis that ozone depletion can cause climate imbalance, resulting in the greenhouse effect, which would cause the polar glaciers to thaw and flood many territories that are currently in housing conditions.

Anyway, scientists' biggest concern is even with skin cancer, whose incidence has been increasing over the last twenty years. Increasingly, it is advised to avoid the sun when it is very strong, as well as using sunscreens, the only ways to prevent and protect the skin.

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