Exercise 2. Underline all initial clusters in the passage. The harmful consequences of ozone deterioration paved the way to the adoption of the Montreal Protocol in 1987. This protocol bans the production of CFCs, halons, and other ozone-depleting chemicals. The ban came into effect in 1989 and since then it has had positive effects on the environment. Ozone levels stabilized by the mid-1990s and began to recover in the 2000s. Recovery is projected to continue over the next century, and the ozone hole is expected to reach pre-1980 levels by around 2075. The Montreal Protocol is considered the most successful international environmental agreement to date.