Potential effects of halons on stratospheric O3 based on the Montreal protocol

A one-dimensional model has been used to calculate the O3 depletion expected if all nations adhere to the Montreal protocol. Assuming estimates of about 10 kt/a for CBrClF2 and CBrF3 production rates, a steady-state column O3 depletion of about 9 percent is calculated for a scenario without increasing N2O and CH4. Approximately 50 percent of this depletion is attributable to halon release. It is suggested that the Montreal protocol should be modified to include a reduction in the production of halons, and that strategies for the recovery and recycling or the destruction of halons should be investigated.