Ground-Level Ozone in Troposphere

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Ground-Level Ozone in Troposphere

GS Paper IIIClimate ChangeEnvironment
Ground-Level Ozone in Troposphere

A recent analysis highlights that ground-level ozone is emerging as a major air pollution challenge in Delhi. The news focuses on its formation in the troposphere, key sources, impacts, and safe limits under WHO Standards and National Ambient Air Quality Standard (NAAQS), 2009.

Ground-Level Ozone (O3) in Troposphere:

Dimension Key Details
Type Ground-level ozone (O3) comprises a secondary air pollutant found in the troposphere.
Formation Ground-level ozone is formed by reactions between Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs) in the presence of sunlight: NOx + VOCs + Sunlight → Ozone (O3).
Major sources Major sources comprise vehicles, industries, and thermal power plants.
Seasonal pattern Ground-level ozone peaks during summer due to intense solar radiation.
Impacts Impacts comprise respiratory ailments, crop damage, and photochemical smog.
Ozone type comparison Stratospheric ozone comprises “Good Ozone” that shields Earth from UV rays, while ground-level ozone comprises a harmful pollutant (“Bad Ozone”).
Safe limit Safe limit provides for 100 µg/m3 for 8-hourly monitored value and 180 µg/m3 for 1-hourly monitored value under WHO Standards and National Ambient Air Quality Standard (NAAQS), 2009.
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Q 1 / 3

With reference to ground-level ozone in the troposphere, consider the following statements:

1. It is a secondary air pollutant.
2. It is formed by reactions between NOx and VOCs in the presence of sunlight.
3. It is also termed “Good Ozone” because it shields Earth from UV rays.

Which of the statements given above are correct?