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Why is bromomethane considered an ozone-depleting substance?

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organohalogen compound Vinyl chloride is an organohalogen compound that has important industrial applications. When treated with certain catalysts, vinyl chloride monomers undergo polymerization and form the larger compound known as polyvinyl chloride, or PVC. PVC is used in the manufacture of numerous products, including packaging films and water pipes.

Bromomethane, also known as methyl bromide, is considered an ozone-depleting substance because it acts as a source of bromine atoms in the stratosphere.1

Similar to chlorofluorocarbons (CFCs), which release chlorine, bromomethane releases bromine atoms when exposed to ultraviolet radiation in the stratosphere. These bromine atoms are highly effective at destroying ozone molecules by stripping away oxygen atoms, a process that leads to the thinning of the ozone layer. Because the ozone layer is essential for blocking harmful solar radiation, the depletion caused by such halocarbons poses significant risks to human health and ecosystems.12

Due to its role in ozone depletion, the use of bromomethane—which has historically been used as a soil fumigant—has been subject to international regulation under the Montreal Protocol on Substances That Deplete the Ozone Layer, which mandates its phase-out.12