The Bio Brief

Human beings are an important part of the environment.

• Changes in the environment affect us
• Our activities also change the environment

Many human activities cause pollution and environmental problems.
In this chapter, we study two major environmental issues:

1. Depletion of the Ozone Layer
2. Waste Disposal (Garbage Management)

1. OZONE LAYER AND ITS DEPLETION

What is Ozone?

• Ozone (O₃) is made of three oxygen atoms
• Normal oxygen (O₂) is essential for life
• Ozone is poisonous at ground level, but very useful in the upper atmosphere

Role of the Ozone Layer

• Found in the upper atmosphere
• Protects the Earth from harmful ultraviolet (UV) rays from the Sun
• UV rays can cause:
  • Skin cancer
  • Eye damage
  • Harm to plants and animals

Formation of Ozone (Simple Diagram)

UV Rays

   ↓

O₂ (Oxygen) → O + O

   ↓

O + O₂ → O₃ (Ozone)

Decrease in Ozone Layer

What Happened to the Ozone Layer?

• In the 1980s, scientists noticed that the amount of ozone in the atmosphere was decreasing rapidly
• This was a serious environmental problem

Main Cause of Ozone Depletion

• The decrease in ozone was linked to synthetic chemicals called Chlorofluorocarbons (CFCs)
• CFCs were used in:
  • Refrigerators
  • Air conditioners
  • Fire extinguishers
  • Spray cans

CFCs rise into the atmosphere and destroy ozone molecules

Flow Chart: Ozone Depletion by CFCs

Use of CFCs

    ↓

CFCs released into air

    ↓

Reach upper atmosphere

    ↓

Destroy ozone layer

    ↓

More UV rays reach Earth

Global Action Taken

• In 1987, the United Nations Environment Programme (UNEP) took action
• An international agreement was made to:
  • Stop increasing the production of CFCs
  • Keep CFC production at 1986 levels

Present Situation

• It is now compulsory for companies to:
  • Manufacture CFC-free refrigerators
  • Use environment-friendly alternatives

Why Was This Important?

• Protects the ozone layer
• Reduces harmful UV radiation
• Prevents skin cancer and eye damage
• Protects plants and animals

Key Points to Remember

• Ozone depletion started in the 1980s
• CFCs were the main cause
• UNEP led global action in 1987
• CFC-free appliances are now mandatory