[op-ed snap] The much-neglected pollutant: Surface Ozone

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Mains Paper 3: Environment | Conservation, environmental pollution and degradation, environmental impact assessment

From UPSC perspective, the following things are important:

Prelims level: Surface ozone

Mains level: Pollution is a hot topic of discussion these days. Surface ozone is one of the many gases which are contributing to pollution levels in India.


News

What is the issue?

  1. A much-neglected pollutant in discussions about pollution is surface ozone (O3)
  2. A recent study shows that O3 levels will continue to rise drastically, particularly in north India

Prevalence of the Ozone gas

  1. The Energy and Resources Institute (New Delhi), the Indian Institute of Tropical Meteorology (Pune) with some foreign institutions analysed the prevalence of O3 in the subcontinent
  2. Their paper, “Impact of regional climate change and future emission scenarios on surface O3 and PM2.5 over India”, was published in the journal Atmospheric Chemistry and Physics
  3. The researchers examined the rise of pollutants due to
    a) anthropogenic pressures and inorganic aerosols, and
    b) climate change which affects atmospheric conditions which have diluted or dispersed the pollutants

Future predictions

  1. In terms of climate change-driven variations, by the 2050s, ozone levels will increase by up to 4.4% (or by 2 parts per billion) in large swathes of north India, particularly Uttar Pradesh

Other factors affecting ozone levels

  1. There will be a decrease over forest patches of the Western Ghats in the south of 3.4% (1.4 parts per billion)
  2. Climate change will adversely impact soil moisture, rains, or vegetation density, which will further impact the absorption of ozone
  3. The scenario is scarier when tabulating man-made sources such as vehicles, power plants, or any machinery that uses fossil fuels, where the O3 component will increase by up to 45% in parts of north India “in the absence of a policy effort” to curb the pollutant

Back2basics

Surface ozone

  1. Ozone (O3) is a constituent of the troposphere (it is also an important constituent of some regions of the stratosphere commonly known as the ozone layer)
  2. The troposphere extends from the Earth’s surface to between 12 and 20 kilometers above sea level and consists of many layers
  3. Ozone is more concentrated above the mixing layer, or ground layer. Ground-level ozone, though less concentrated than ozone aloft, is more of a problem because of its health effects.
  4. Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night
  5. At abnormally high concentrations brought about by human activities (largely incomplete combustion of fossil fuels, such as gasoline, diesel, etc.), it is a pollutant, and a constituent of smog
  6. Many highly energetic reactions produce it, ranging from combustion to photocopying. Often laser printers will have a smell of ozone, which in high concentrations is toxic
  7. Ozone is a powerful oxidizing agent readily reacting with other chemical compounds to make many possibly toxic oxides
  8. Tropospheric ozone is a greenhouse gas and initiates the chemical removal of methane and other hydrocarbons from the atmosphere
  9. Thus, its concentration affects how long these compounds remain in the air
Air Pollution
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