Context:

• The European Space Agency Copernicus Sentinel-5P satellite made the recordings of a large ozone hole over Antarctica as part of the EU’s environmental monitoring program.

What is ozone hole and how is it caused?

• The ozone hole is not technically a “hole” where no ozone is present, it is the region over Antarctica with a total ozone of 220 Dobson Units or lower in the stratosphere. 
  • The Dobson Unit is the most common unit for measuring ozone concentration.

• Size: The size of the ozone hole over Antarctica fluctuates each year, opening each year in August and closing again in November or December. 
  • This hole was 26 million square kilometers in size, roughly three times the size of Brazil, one major reason may be the volcanic eruptions at Hunga Tongain Tonga. 
• Climate Change: Experts believe the hole in the ozone is not likely to increase warming on the surface of Antarctica and is not a concern for climate change.
• Ozone Holes Grow and Shrink Every Year: The ozone hole opens up because of the rotation of the Earth causing special winds over the closed landmass of Antarctica. 
  • The winds create a mini climate, creating a shield over Antarctica preventing it from mixing with surrounding air. When the winds die down, the hole closes.
• Montreal Protocol: The world took action after scientists raised alarm over the ozone holes. In 1987, Montreal Protocol was created to protect the ozone layer by phasing out the production of these harmful substances.

Ozone Layer

• The ozone layer is a trace gas which sits in the stratosphere between 15 km and 30 km above the earth. 
• It functions as a protective gas shield that absorbs ultraviolet radiation (UV), protecting humans and ecosystems from dangerous amounts of UV. 
  • Most skin cancers are caused by exposure to high amounts of UV radiation.

• Bad Ozone: Ozone at ground level is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog”.

News Source: The Indian Express

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