The maximum hole size of the ozone layer reached this year has been about 19.7 million square kilometers, the equivalent of two and a half times the area of ​​the United States. The data corresponds to the month of September and, although it may sound dangerous, the truth is that the opening is 4.4 million kilometers smaller than on the same dates of 2016.
As reported recently by NASA, the size of the huge orifice located over Antarctica has decreased since last year to reach a minimum recorded for the last time 1988. The reduction is due, to a large extent, to the unusual increase in temperature in the stratosphere : hot air prevents the formation of polar stratospheric clouds that favor the reactions of chemicals such as color and bromine that cause deterioration of the gaseous shield.
Likewise, the scientists point out as another cause the efforts carried out since the eighties to prohibit the emission into the atmosphere of substances that damage the ozone layer.
The good news comes shortly after the thirtieth anniversary of the discovery of the hole, a finding that prompted the signing of the Montreal Protocol in 1987, an international treaty to ban the use of chemicals such as chlorofluorocarbons (CFCs) that destroy the sheet that protects to the planet of radiation.
However, the significant reduction in the size of the hole can not be interpreted as an absolute victory. The loss and formation of ozone depend on the climatic conditions and, therefore, can vary a lot from year to year, as happens with other phenomena such as hurricanes.
In addition, a study published in 'Nature Communications' only a few months ago warned about the potential danger of an industrial chemical known as dichloromethane, whose concentration in the atmosphere has doubled in the last ten years. If the amount of this compound that destroys the ozone layer continues to increase, the final recovery of the hole could be delayed several decades.
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