Justify the need for signing of 'Montreal Protocol' by the participating nations in 1987.

Explanation

### Step-by-Step Solution:

1. **Introduction to the Montreal Protocol**:
The Montreal Protocol was signed in 1987 in Montreal, Canada, by various nations to address the critical issue of ozone layer depletion caused by certain substances.

2. **Understanding Ozone Layer Depletion**:
The ozone layer is a protective shield in the Earth's stratosphere that absorbs the majority of the sun's harmful ultraviolet (UV) radiation. The depletion of this layer poses significant risks to human health and the environment.

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