By Sebastien Malo
NEW YORK, May 18 (Thomson Reuters Foundation) - Scientists are hunting for the mysterious source of surging levels of a gas that is outlawed for depleting the planet's protective ozone layer, United Nations officials said on Friday.
Production of the banned gas should be near zero but recent findings showed an increase in the atmosphere of 25 percent since 2012, according to a report published this week in the academic journal Nature.
Research points to it originating in East Asia, experts said.
The gas, trichlorofluoromethane, or CFC-11, was once commonly used in refrigerators and spray cans and has industrial uses.
U.N. experts want to "tighten down" the source of the gas emissions by fall, said Paul Newman, co-chairman of a panel helping enforce the agency's Montreal Protocol that bans ozone-depleting chemicals.
The planet's ozone layer shields life from cancer-causing solar rays.
CFC-11 is undetectable using common infrared techniques so scientists plan to utilize monitoring stations and aircraft observations, Newman said.
But pinpointing the exact location will be difficult, he told the Thomson Reuters Foundation.
"You really have to get nearby the production facilities themselves and find the stuff," he said.
No country has been known to violate the Montreal Protocol in its 30 years of existence, said David Fahey, also a member of the treaty's assessment panel.
"There's certainly somebody who is responsible in that part of the world, but it could be inadvertent," he told the Foundation.
In addition to damaging to the ozone layer, CFC-11 is also a planet-warming greenhouse gas thousands of time more potent than carbon dioxide, scientists say.
(Reporting by Sebastien Malo @sebastienmalo, Editing by Ellen Wulfhorst)
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