It refers to the phenomenon that the atmospheric ozone layer is destroyed and reduced due to the diffusion and erosion of atmospheric pollutants, especially aerosol pollutants such as nitrogen oxides and halogenated hydrocarbons. There is a thin layer of ozone layer above the earth's atmosphere, which is 20 ~ 25 kilometers from the ground and below the stratosphere. It is the most effective "protective umbrella" to resist ultraviolet radiation from the sun and protect the earth's biosphere. However, since scientists first discovered ozone depletion over Antarctica in 1982, similar ozone holes have been found over the Arctic and the Qinghai-Tibet Plateau, and ozone depletion has occurred all over the world except the tropical regions. After tracking and monitoring, scientists found the cause of ozone hole: a large number of chlorofluorocarbons used as refrigerants, sprays, foaming agents and other chemicals are the "culprit" leading to ozone reduction. In addition, cold is also the key to the thinning of the ozone layer, which is why the ozone hole first appeared in the coldest areas of the earth's north and south poles.
According to a recent observation provided by the World Meteorological Organization, compared with the ozone holes from 1964 to 1976, the ozone layer at each pole over Antarctica has decreased by 20% ~ 30% respectively, and the ozone hole is likely to continue to expand this year. It will take at least 20 years for the Antarctic ozone layer to recover obviously, and it is estimated that the ozone hole will not be completely eliminated until 2050.
/s？ ie = GB 23 12 & amp； bs = % B0 % AE % D2 % F2 % CB % B9 % CC % B9 % C6 % E6 % BC % A3 % C4 % EA % CA % C7 % D4 % F5 % d 1% F9 % B7 % A2 % C9 % FA % B5 % C4 & amp； sr = & ampz = & ampcl = 3 & ampf = 8 & ampwd = % B3 % F4 % d 1% F5 % BF % D5 % B6 % B4 & amp； ct=0