The weakened ozone layer, which is vital to protecting life on Earth, is on track to be restored to full strength within decades — the latest success of a global effort by nations to stop using chemicals that had been destroying the critical layer in the upper atmosphere.
In a report for the United Nations, scientists said Monday that China had largely eliminated rogue emissions of one of those chemicals, known as CFC-11.
Once widely used as a refrigerant and in foam insulation, CFC-11 was first synthesized a century ago. Along with similar chemicals, collectively called chlorofluorocarbons, CFC-11 destroys ozone, which blocks ultraviolet radiation from the sun that can cause skin cancer and otherwise harm people, plants and animals. Chlorofluorocarbons were banned under the Montreal Protocol, a landmark environmental agreement that took effect in 1989.
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