<human>: How are ozone depleting chemicals being eliminated?
<bot>: Ozone depleting chemicals are being phased out of production and use. The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty that was signed in 1987 to protect the ozone layer by reducing emissions of certain substances, such as chlorofluorocarbons (CFCs) and halons. As a result, the concentration of these compounds has been reduced significantly since the 1980s.