Ozone gets depleted in the stratosphere due to the presence of

Ozone depletion in the stratosphere is primarily driven by catalytic cycles involving reactive halogen species. Chlorofluorocarbons (CFCs) and other ozone-depleting substances release free chlorine atoms when exposed to ultraviolet radiation [c2, c3]. These 'active' chlorine radicals (Cl) initiate a chain reaction where a single chlorine atom can destroy over 100,000 ozone molecules [c2, t7]. The process involves the chlorine atom reacting with ozone (O3) to form chlorine monoxide (ClO), which then reacts with atomic oxygen to reform the active chlorine atom, allowing the cycle to repeat [c3, t1]. While nitrogen oxides (NOx) also participate in ozone chemistry, active chlorine is the dominant driver of the significant depletion observed in the Antarctic ozone hole and global stratospheric trends [c1, t8]. Other species like SO2 are more relevant to tropospheric chemistry and acid rain rather than direct stratospheric ozone destruction [t4, t6].

Sources

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