Common air pollutants: ground-level ozone

Common air pollutants: ground-level ozone

News Analysis   /   Common air pollutants: ground-level ozone

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Published on: June 10, 2023

Source: The Indian Express


According to a new report by the Centre for Science and Environment (CSE), ground-level ozone levels in the Delhi-NCR region exceeded national guidelines on 87 of 92 days between March and May 2023.

Findings from the report:

  1. Ground-level ozone pollution in Delhi-NCR was lower in 2023 compared to the previous five years, but the duration of its exceedance has increased. This is a cause for concern as elevated ozone levels persist even after sunset, contrary to expectations.
  2. Stations reporting exceedance of ozone levels had an average rolling 8-hour average above the standard for 4.9 hours on average this summer, compared to 4.6 hours observed last summer.
  3. Ozone pollution is not limited to specific seasons. Even during the winter months when cold and foggy conditions inhibit ground-level ozone formation, Delhi-NCR experienced excess ozone levels on multiple days in January 2023.

Ozone levels exceeded the standard at multiple stations for 26 days in January 2023.

The areas most affected by ground-level ozone pollution were New Delhi and South Delhi.

Ground-Level Ozone

  • Ground-level ozone, also known as tropospheric ozone, is a colorless and highly irritating gas that forms near the Earth’s surface.
  • It is generated through complex interactions between nitrogen oxides (NOx), volatile organic compounds (VOCs), and carbon monoxide emitted from various sources.
  • Vehicles, power plants, factories, and other combustion sources release these pollutants into the atmosphere.
  • Under sunlight, these compounds undergo cyclic reactions that result in the formation of ground-level ozone.

Impact of Ground-Level Ozone:

  1. Ground-level ozone is considered a significant air pollutant.
  2. It can have detrimental effects on human health, vegetation, and ecosystems.
  3. When nitrogen oxides (NOx) and volatile organic compounds (VOCs) interact in the presence of sunlight, they undergo chemical reactions that lead to the production of ground-level ozone.
  4. High levels of ozone can cause respiratory issues, worsen asthma and other respiratory conditions, and contribute to lung diseases in humans.
  5. It can also harm crops, forests, and other vegetation, affecting agricultural productivity and ecosystem balance.

Efforts to Address Ground-Level Ozone:

Monitoring and controlling ground-level ozone levels are important for mitigating its harmful effects on human and environmental health.

Strategies include reducing emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) from sources such as vehicles, industries, and power plants.

Implementing air quality regulations, adopting cleaner technologies, and promoting sustainable practices can help minimize the formation and impact of ground-level ozone.

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