Final answer:
Chlorofluorocarbons, hydrochlorofluorocarbons, hydrobromofluorocarbons, and halons are ozone-depleting substances and greenhouse gases, contributing to stratospheric ozone depletion and global warming respectively. They are being phased out under international agreements like the Montreal Protocol.
Step-by-step explanation:
Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrobromofluorocarbons (HBFCs), and halons are compounds that have historically been used in various industrial applications due to their stability and non-reactive properties. However, they are ozone-depleting substances that contribute to the thinning of the ozone layer in the stratosphere. The loss of the ozone layer exposes the Earth to higher levels of harmful ultraviolet (UV) radiation. CFCs and other related compounds are also considered greenhouse gases because they trap heat in the Earth's atmosphere, leading to a warming effect. They are not typically known as water or air pollutants in the conventional sense, as they don't often directly impact water or air quality at ground level.
Under international environmental treaties like the Montreal Protocol, the production and use of CFCs, HBFCs, and related compounds have been phased out and replaced with other, less harmful substances, such as hydrofluorocarbons (HFCs). Despite the phasing out, these compounds have long atmospheric lifetimes and continue to persist in the environment. The efforts to reduce their use and release have been effective in starting the recovery of the ozone layer.