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whEn sCiEntists First wArnED in thE 1970s thAtCFCs CoulD AttACk ozonE, thE u.s. rEsponDED By BAnning thEir usE in sprAy CAns.But thE rEst oF thE worlD ContinuED to usECFC、-BAsED AErosol CAns, AnD ovErAllCFC、proDuCtion kEpt growing. thE thrEAt BECAmE FAr ClEArEr in 1985, whEn rEsEArChErs rEportED A "holE" in thE ozonE lAyEr ovErAntArCtiC、Although thE sizE oF thE BolE vAriEs with thE sEAsons AnD wEAthEr pAttErns, At timEsAntArCtiC ozonE hAs BEEn DEplEtED By As muCh As 50% in somE spots.As A rEsult oF this DisturBing DE- vElopmEnt,24 nAtions, inCluDing thE u. s. AnD thE soviEt union, mEt in montrEAl two summErs Ago AnD A- grEED to Cut BACk onCFCs. thE so - CAllED montrEAl protoCAl is DEsignED to AChiEvE A 35% nEt rEDuCtion in worlDwiDECFC、proDuCtion By 1999.
thAt’s not gooD Enough, howEvEr, thE sAmE stABility thAt mAkEsCFC、so sAFE in inDustriAl usE mAkEs thEm ExtrEmEly longlivEs, somE oF thECFCs rElEAsED toDAy will still BE in thE AtmosphErE A CEntury From now. morEovEr, EACh Atom oF ChlorinE liBErAtED Form ACFC、CAn BrEAk up As mAny As 100,000 molECulEs oF ozonE.
For this rEAson, govErnmEnts shoulD EnsurE thE CArEFul hAnDling AnD rECyCling oF thECFC、now in usE. whEn plAstiC-FoAm BurgEr holDErs ArE BrokEn, thECFCs trAppED insiDE EsCApE.DisCArDED rEFrigErAtors rE- lEAsECFCs As wEll, AnD, A signiFiCAnt pArt oF thE u.s. ContriBution toCFC、Emissions ComEs From DrAining AutomoBilE Air ConDitionErs. suCh rElEAsE oFCFCs CoulD BE prEvEntED iF ConsumErs AnD BusinEssEs wErE oFFErED CAsh inCEntivEs to rEturn BrokEnDown Air ConDitionErs AnD rEFrigErAtors to Auto AnD AppliAnCE DEAlErs. thEn thE units CoulD BE sEnt BACk to thE mAnuFACturErs so thAt thECFCs CoulD BE rEusED、
whilE rECyCling will hElp, thE only surE wAy to sAvE thE ozonE is A ComplEtE BAn onCFC、mAnuFACturE, whiCh shoulD BE phAsED out ovEr thE nExt FivE yEArs. FortunAtEly, As thE montrEAl protoCAl DEmonstrAtEs, BAnningCFCs will BE FAr simplEr thAn rEDuCing othEr DAngErous gAsEs.But A BAn CoulD ADmittEDly BE EConomiCAlly DisruptivE to thE EntirE worlD: thE AnnuAl mArkEt ForCFCs is somE $ 2.2 Billion. thE soviEt union, whiCh is A hEAvy usEr oFCFCs, will hAvE A pArtiCulArly tough timE phAsing out thE ChEmiCAls. "i AgrEE with thE BAn in prinCiplE, "sAiD vlADimir sAkhArov, A mEmBEr oF thE soviEt stAtECommittEE ForEnviromEntAl protECtion, "But in prACtiCE it will BE ExtrEmEly DiFFiCult. our EConomy is not FlExiBlE As othErs."
to mAkE thE trAnsition EAsiEr, ChEmiCAl CompAniEs ArE working hArD to FinD prACtiCAl suBstitutEs ForCF-Cs. thE most promising ApproACh so FAr is to usECFC、FAmily mEmBErs thAt ArE ChEmiCAlly AltErED to mAkE thEm lEss DAngErous to thE EnvironmEnt. thE ChlorinE - FrEE suBstitutEs is thE high Cost oF mAking thEm. it mAy BE thAt until BEttEr mAnuFACturing tEChniquEs ArE DEvElopED, ConsumErs will hAvE to pAy morE For AFFECtED proDuCts. thE prospECt is not A plEAsAnt onE, it is A smAll priCE to pAy For CurBing tilE grEEn housE EFFECt AnD sAving thE liFE -prEsErving ozonE lAyEr.
thE BEst wAy to sAvE ozonE is ______.A．thAtCFC、mAnuFACturE is ComplEtEly ForBiDDEn
B．thAt thE proDuCtion oFCFC、is rEDuCED
C．to FinD suBstitutEs ForCFCs
D．to rEDuCE thE DAngEr oFCFCs