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Low ozone over Brahmaputra River Valley

Topics Covered: Conservation and pollution related issues.

Low ozone over Brahmaputra River Valley:


Researchers have found that the concentration of near surface ozone in this region is low compared to the other urban locations in India.

What is Tropospheric or ground-level ozone?

It is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). It usually increases when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight, impacting human health.

Why low ozone in Brahmaputra Valley?

This site is well influenced by local sources such as adjacent major national highway. During the daylight hours, the site is in or nearly in a photo-stationary state, indicating a low impact of organic species on the ozone concentrations.

Why we should be concerned about ground-level 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.”
  • Elevated ground-level ozone exposures affect agricultural crops and trees, especially slow growing crops and long-lived trees.
  • The main health concern of exposure to ambient ground-level ozone is its effect on the respiratory system, especially on lung function.


Ozone is produced naturally in the stratosphere when highly energetic solar radiation strikes molecules of oxygen, and cause the two oxygen atoms to split apart in a process called photolysis. If a freed atom collides with another O2, it joins up, forming ozone.


Prelims Link:

  1. What is Ozone?
  2. Tropospheric GS Stratospheric ozone.
  3. How ground level ozone is formed?
  4. Role of Ozone in the formation of smog.
  5. What are VOCs?

Mains Link:

Discuss the health concerns associated with the formation of ozone at the ground level.

Sources: pib.