Ground Level Ozone
Why in news:
- According to a new analysis by the Centre for Science and Environment (CSE), parts of the Delhi-NCR region witnessed ground-level ozone readings exceeding the national standards on 87 out of 92 days in the summer period between March and May.
- The worst affected parts in the area are New Delhi and South Delhi neighbourhoods.
- Moreover, the region is seeing a rare phenomenon where ozone levels remain elevated hours after sunset ground-level ozone should ideally become negligible during the night.
- Another issue is that the pollutant, which once used to be prominent only during the summers, has become a yearlong problem.
What is ground-level ozone?
- As per Environment and Climate Change Canada (ECCC) ground-level ozone is “a colourless and highly irritating gas that forms just above the Earth’s surface (up to 2 miles above the ground).”
- It is also known as tropospheric ozone.
- It’s not directly emitted into the air but rather produced when two primary pollutants react in sunlight and stagnant air.
- These two primary pollutants are nitrogen oxides (NOx) and volatile organic compounds (VOCs).
- Therefore, ground-level ozone is called a “secondary” pollutant.
- NOx and VOCs come from natural sources as well as human activities.
- About 95 per cent of NOx from human activity comes from the burning of coal, gasoline and oil in motor vehicles, homes, industries and power plants.
- VOCs from human activity come mainly from gasoline combustion and marketing, upstream oil and gas production, residential wood combustion, and from the evaporation of liquid fuels and solvents.
What are the harmful effects of ground-level ozone?
- The CSE analysis said as ground-level ozone is a highly reactive gas, it has serious health consequences.
- Those with respiratory conditions, asthma, chronic obstructive pulmonary disease, and particularly children with premature lungs and older adults are at serious risk.
- This can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema, and chronic bronchitis and increase the frequency of asthma attacks leading to increased hospitalisation.
- The pollutant can also affect sensitive vegetation and ecosystems, including forests, parks and wildlife refuges.
- Significantly, it can harm sensitive vegetation during the growing season too.
Syllabus: Prelims; Environment