The Centre for Science and Environment (CSE) has conducted a new analysis revealing a dramatic increase in ground-level ozone pollution within the Delhi-NCR region. The data indicates that this region exceeded national standards for ground-level ozone on 87 out of 92 days between March and May 2023. The CSE is a research and advocacy organisation based in New Delhi, dedicated to promoting sustainable and equitable development through research, lobbying, and communicative efforts.
Ozone Pollution Duration of Exceedance
Despite the fact that the 2023 ground-level ozone pollution was lower than the previous five years, the duration of exceedance showed an upward trend. Elevated ozone levels remained high even several hours after sunset, posing unexpected risks to public health. The average exceedance saw ozone levels stay above standard for 4.9 hours, up from 4.6 hours observed during the same period last year.
Ozone Pollution Across Seasons
Contrary to popular belief, ozone pollution is not confined to specific seasons. Even during winter months, known for inhibiting ground-level ozone formation thanks to cold and foggy conditions, Delhi-NCR recorded excess ozone levels on numerous days in January 2023. In total, ozone levels exceeded the standard at multiple stations on 26 days during this month.
The Most Affected Areas
The regions of New Delhi and South Delhi were found to be most affected by ground-level ozone pollution.
Understanding Ground-Level Ozone
Ground-level ozone, or Tropospheric ozone, is a colorless and highly irritating gas that forms near the Earth’s surface. It is not directly emitted but forms through complex interactions between Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs), and carbon monoxide. These compounds, mainly emitted from vehicles, power plants, factories, and other combustion sources, undergo cyclic reactions in the presence of sunlight to form ground-level ozone.
Impact of Ground-Level Ozone
When NOx and VOCs interact under sunlight, they form ground-level ozone through complex chemical reactions. As a major air pollutant, ground-level ozone can have harmful effects on human health, vegetation, and ecosystems.
Initiatives Against Ground-Level Ozone Pollution
Various initiatives have been undertaken to combat ground level ozone pollution. These include the commission for Air Quality Management in National Capital Region (NCR) and Adjoining Areas, Bharat Stage (BS) VI norms, Dashboard for Monitoring Air Quality, National Clean Air Programme, National Air Quality Index (AQI), and the Air (Prevention and Control of Pollution) Act, 1981.
UPSC Civil Services Examination Previous Year Question (PYQ)
This question from the 2019 exams asked candidates to identify which compounds – Carbon monoxide, Methane, Ozone, and Sulphur dioxide – are released into the atmosphere due to the burning of crop/biomass residue. The correct answer is all four.