MCQ Detailed View

The ozone layer is a protective shield in the stratosphere that absorbs most of the harmful ultraviolet (UV) radiation from the sun. Without it, life on Earth would be exposed to dangerous levels of UV rays, leading to increased cases of skin cancer, cataracts, and damage to ecosystems. For decades, scientists identified chlorofluorocarbons (CFCs) as the main culprit behind ozone depletion. These man-made chemicals were widely used in refrigeration, air conditioning, and aerosol sprays.

However, more recent research has highlighted another significant threat: Nitrous Oxide (N₂O). This gas is now considered the new and most important culprit damaging the ozone layer. Unlike CFCs, which are being phased out under international agreements like the Montreal Protocol, nitrous oxide emissions continue to increase due to human activities.

Nitrous oxide is released mainly from agricultural practices, especially the use of nitrogen-based fertilizers. It is also produced by the burning of fossil fuels, industrial processes, and certain natural sources like soil and oceans. When nitrous oxide reaches the stratosphere, it undergoes chemical reactions that release nitrogen oxides (NO and NO₂). These compounds accelerate the breakdown of ozone molecules, reducing the concentration of ozone in the stratosphere.

What makes nitrous oxide particularly concerning is that it has a dual impact:

1. 
   

   It is a potent greenhouse gas, trapping heat in the atmosphere and contributing to climate change.

   
   


2. 
   

   It is now the largest ozone-depleting emission not yet controlled by international treaties.

   
   

In summary, while CFCs were once the main cause of ozone layer damage, today Nitrous Oxide (N₂O) is recognized as the most important and emerging threat. Reducing nitrous oxide emissions, especially from agriculture, is vital for protecting the ozone layer and combating global climate change.