On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short‐Lived Substances

Chloroform (CHCl 3 ), dichloromethane (CH 2 Cl 2 ), perchloroethylene (C 2 Cl 4 ), and 1,2‐dichloroethane (C 2 H 4 Cl 2 ) are chlorinated Very Short‐Lived Substances (Cl‐VSLS) with a range of commercial/industrial applications. Recent studies highlight the increasing influence of Cl‐VSLS on the stratospheric chlorine budget and therefore their possible role in ozone depletion. Here we evaluate the ozone depletion potential (ODP) of these Cl‐VSLS using a three‐dimensional chemical transport model and investigate sensitivity to emission location/season. The seasonal dependence of the ODPs is small, but ODPs vary by a factor of 2–3 depending on the continent of emission: 0.0143–0.0264 (CHCl 3 ), 0.0097–0.0208 (CH 2 Cl 2 ), 0.0057–0.0198 (C 2 Cl 4 ), and 0.0029–0.0119 (C 2 H 4 Cl 2 ). Asian emissions produce the largest ODPs owing to proximity to the tropics and efficient troposphere‐to‐stratosphere transport of air originating from industrialized East Asia. The Cl‐VSLS ODPs are generally small, but the upper ends of the CHCl 3 and CH 2 Cl 2 ranges are comparable to the mean ODP of methyl chloride (0.02), a longer‐lived ozone‐depleting substance.