Fri, May 24, 2019 - Page 1 News List

Ozone-depleting gases coming from PRC, scientists say


Industries in northeastern China have spewed large quantities of an ozone-depleting gas into the atmosphere in contravention of an international treaty, scientists said on Wednesday.

Since 2013, annual emissions from northeastern China of the banned chemical trichlorofluoromethane, or CFC-11, have increased by about 7,000 tonnes, they reported in the journal Nature.

“CFCs are the main culprit in depletion of the stratospheric ozone layer, which protects us from the sun’s ultraviolet radiation,” said lead author Matt Rigby, an atmospheric chemist at the University of Bristol in Britain.

CFC-11 was widely used in the 1970s and 1980s as a refrigerant and to make foam insulation. The 1987 Montreal Protocol banned CFCs and other industrial aerosols that chemically dissolve protective ozone 10 to 40km above Earth’s surface, especially over Antarctica and Australia.

Following the ban, global concentrations of CFC-11 declined steadily until about 2012, but last year startled scientists discovered that the pace of that slowdown dropped by half from 2013 to 2017.

Because the chemical does not occur in nature, the change could only have been produced by new emissions.

Evidence pointed to East Asia, but scientists could not nail down the exact origin.

“Our monitoring stations were set up in remote locations far from potential sources,” said coauthor Ron Prinn, a professor at the Massachusetts Institute of Technology.

Reports last year from non-governmental organization the Environmental Investigation Agency fingered Chinese foam factories in the coastal province of Shandong and the inland province of Hebei, which surrounds Beijing.

Suspicions were strengthened when authorities subsequently shut down some of the facilities without explanation.

To probe further, an international team of atmospheric scientists gathered additional data from monitoring stations in Taiwan and Japan.

“Our measurements showed ‘spikes’ in pollution when air arrived from industrialized areas” in China, said another lead author, Park Sun-young of Kyungpook National University in South Korea.

The team also ran computer simulations that confirmed the origin of the CFC-11 molecules.

“We didn’t find evidence of increased emissions from Japan, the Korean Peninsula or any other country,” added Luke Western, a post-doctoral researcher at the University of Bristol.

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