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Ozone pollution spiked in several cities during lockdown

Topics Covered: Conservation, environmental pollution and degradation, environmental impact assessment.

Ozone pollution spiked in several cities during lockdown


According to an analysis by the Centre for Science and Environment (CSE), while particulate matter and nitrous oxide levels fell during the lockdown, ozone — also a harmful pollutant — increased in several cities.

Factors responsible for tropospheric ozone pollution:

Ozone is primarily a sunny weather problem in India that otherwise remains highly variable during the year.

The surge is because of few characteristics of summer pollution. These include: high winds, intermittent rains and thunderstorms, and high temperature and heat waves.

What is Ozone?

Ozone (O3) is a colourless, reactive oxidant gas that is a major constituent of atmospheric smog.

How Tropospheric, or ground level ozone is formed?

Ozone is not directly emitted by any source but is formed by photochemical reactions between oxides of nitrogen (NOx) and other volatile organic compounds (VOCs) and gases in the air under the influence of sunlight and heat.

This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.


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.



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: the Hindu.