By Jung Min-ho
The ozone layer that shields Earth from the sun’s harmful ultraviolet rays is showing clear signs of thickening after years of dangerous depletion, scientists said Thursday.
According to the Korea Meteorological Administration (KMA), the thickness of the ozone layer over Northeast Asia observed from Korea increased to 325 DU in 2013 from 317 DU in 1985.
One DU (Dobson Unit) is defined to be 0.01 mm thickness at standard temperature and pressure.
The global average ozone thickness is 300 DU, which would correspond to a layer 3 millimeters thick at sea level.
Scientists credit the recovery to the phasing out of harmful ozone chemicals mainly used in refrigerators, air conditioners and aerosol cans after 197 countries, including Korea, signed the Montreal Protocol in 1987 to protect Earth’s vital shield.
According to the KMA, the amount of CFCs has steadily declined since research centers started monitoring CFC levels in 1999.
In their first review in four years on the planet’s ozone layer, U.N. agencies said on Sept. 10 that the 1987 treaty has been successful.
A panel of 300 scientists at the gathering predicted that it will take until 2050 for the ozone layer in the mid-latitudes to return to relatively healthy 1980s conditions. Around the Antarctic, where the ozone layer is the most damaged, it will take until 2075 to reach normal levels, they noted.