2022 winter air in Delhi NCR ‘cleanest’ in five years but ‘toxic’

2022 winter air in Delhi NCR ‘cleanest’ in five years but ‘toxic’

Subject: Environment

Section: Pollution

Context: There was heavy and extended rainfall in the early phases of the season that prevented smog episodes from building up, says CSE report.

More on the News:

• The winter of 2022 was Delhi’s “cleanest” in the last five years, though its air remains “toxic”. The main determinants for the improved air quality were favourable meteorological conditions as well as a reduction in pollution from farm fires, Delhi-based think tank, the Centre for Science and Environment (CSE).
• The improvement is a combined effect of meteorology and emergency action based on pollution forecasting. There was heavy and extended rainfall in the early phases of the season that prevented smog episodes from building up and also lowered the seasonal average.
• The CSE’s numbers, sourced from the Central Pollution Control Board (CPCB), suggest that a factor behind reduced pollution last winter was a drop in instances of ‘severe pollution’. There were only 10 days when air quality was ‘severe’ or ‘severe+’ — the highest levels of pollution. In comparison, there were 24 such days in 2021, 23 in 2020, 25 in 2019, and 33 in 2018.
• Despite the decline, Delhi continues to remain the most polluted among the cities and towns of NCR.

Delhi Air Pollution https://optimizeias.com/soon-delhis-air-pollution-sources-to-be-available-in-real-time/

National Ambient Air Quality Standards

• The mandate provided to the Central Pollution Control Board (CPCB) under the Air (Prevention and Control of Pollution) Act empowers it to set standards for the quality of air.
• Hence the current National Ambient Air Quality Standards were notified in November 2009 by the CPCB.
• Prior to this, India had set Air Quality standards in 1994, and this was later revised in 1998.
• The 2009 standards further lowered the maximum permissible limits for pollutants and made the standards uniform across the nation.
• Earlier, less stringent standards were prescribed for industrial zones as compared to residential areas.
• Pollutants covered:
  1. Sulphur Dioxide (SO2)
  2. Nitrogen Dioxide (NO2),
  3. Particulate Matter (size less than 10 µm) or PM 10
  4. Particulate Matter (size less than 2.5 µm) or PM2.5
  5. Ozone (O3)
  6. Carbon Monoxide (CO)
  7. Ammonia (NH3)
  8. Lead
  9. Benzene (C6H6)
  10. Benzo(a)Pyrene (BaP)
  11. Arsenic(As)
  12. Nickel (Ni)