Ozone layer is un­der new threat, says study

Mint ST - - POLICY - BY MAYANK AGGARWAL mayank.a@livemint.com NEW DELHI

Is the ozone layer fac­ing a new threat? An in­ter­na­tional team of re­searchers has found sub­stances such as di­chloro­meth­ane could en­dan­ger the earth’s frag­ile ozone layer and are not reg­u­lated un­der the cur­rent global treaty to stop pro­duc­tion of ozone-de­plet­ing sub­stances. The claim was made on Thurs­day in a study pub­lished in At­mo­spheric Chem­istry and Physics, a jour­nal of the Euro­pean Geo­sciences Union. The study was car­ried out by an in­ter­na­tional team of re­searchers led by David Oram of Uk-based Univer­sity of East Anglia.

In 1989, the world agreed on a global treaty, the Mon­treal Pro­to­col, to pro­tect the ozone layer by re­duc­ing the pro­duc­tion and con­sump­tion of ozone-de­plet­ing sub­stances.

The study stressed that the Mon­treal Pro­to­col had helped heal the ozone layer, which re­duces the im­pact on hu­man health from in­creased exposure to dam­ag­ing so­lar ra­di­a­tion, but added that in­creas­ing emis­sions of ozone-de­stroy­ing sub­stances that are not reg­u­lated by the Pro­to­col are threat­en­ing the re­cov­ery.

It also raised alarm over fast in­creas­ing emis­sions of some short-lived chem­i­cals in East Asia, and showed how they can be car­ried up into the strato­sphere and dam­age the ozone layer.

“The sub­stances in ques­tion were not con­sid­ered dam­ag­ing be­fore as they were gen­er­ally thought to be too short­lived to reach the strato­sphere in large quan­ti­ties,” said Oram.

As per the study, one of the new threats is di­chloro­meth­ane, a sub­stance with uses rang­ing from paint strip­ping to agri­cul­tural fu­mi­ga­tion and the pro­duc­tion of phar­ma­ceu­ti­cals.

The quan­tity of di­chloro­meth­ane in the at­mos­phere de­creased in the 1990s and early 2000s, but over the past decade it has be­come more abun­dant.

“This was a ma­jor sur­prise to the sci­en­tific com­mu­nity and we were keen to dis­cover the cause of this sud­den in­crease. We ex­pected that the new emis­sions could be com­ing from the de­vel­op­ing world, where in­dus­tri­al­iza­tion has been in­creas­ing rapidly,” said Oram.

He added that their es­ti­mates sug­gest that “China may be re­spon­si­ble for around 50-60% of cur­rent global emis­sions (of di­chloro­meth­ane), with other Asian coun­tries, in­clud­ing In­dia, likely to be sig­nif­i­cant emit­ters as well.”

The sci­en­tists col­lected air sam­ples on the ground in Malaysia and Tai­wan, in the re­gion of the South China Sea between 2012 and 2014 and their anal­y­sis re­vealed pres­ence of “di­chloro­meth­ane in large amounts” and “1,2-dichloroethane”, which is an­other ozone-de­plet­ing sub­stance used to make PVC.

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