New research shows that the ozone layer in low latitudes has not recovered

Although there is some good news about the recovery of the ozone layer recently, a new study shows that the ozone level in densely populated low latitudes does not seem to be recovering as in the polar regions. Although there is no clear explanation, the problem is still due to ozone depleting chemicals, such as those contained in paint removers and degreasers.

The ozone layer acts as the earth's protective barrier to protect humans, animals and plants from harmful ultraviolet radiation. In the 1970s, chlorofluorocarbons used in refrigerators and aerosols were found to be the main reason for the reduction of stratospheric ozone. Finally, in 1987, the use of these compounds was phased out under the provisions of the Montreal Protocol on substances that Deplete the ozone layer.

However, frontier research shows that although the ozone hole over Antarctica is gradually repaired, the ozone hole in the latitude range of 60 ° n to 60 ° s shows no signs of recovery. These latitudes cover densely populated areas from Russia to near Australia.

The study's co-author Joanna Haigh, CO director of the Grantham Institute at Imperial College London, said: "the potential harm in low latitudes may actually be more serious than in the polar regions. Before the promulgation of the Montreal Protocol, the reduction of ozone was less than what we saw at the poles, but ultraviolet radiation was stronger in these regions and more people lived there."

Using the new algorithm and data from various satellite missions carried out since 1985, the research team has created a long-time series to reveal the longer-term trend of ozone reduction at low latitudes and altitudes in the stratosphere between 10 and 50 km (6.2 and 31 miles). Although they can not provide any clear explanation at present, the researchers have put forward some theories.

One theory is that the change of atmospheric circulation model caused by climate change may take more ozone away from the tropics. Another theory is that substances that can only exist briefly in the atmosphere (vslss) are considered to stay in the atmosphere for not long enough to reach the stratosphere and affect the ozone layer, which may be longer than expected.

William ball, from the Federal Institute of technology in Zurich, said: "the discovery of ozone decline at low latitudes is surprising because our current better atmospheric circulation models can not predict this effect. The short-lived substances in the atmosphere may be the missing factor in these models."

The team's paper has been published in the journal Atmospheric Chemistry and physics of the European geoscience Federation.