Call Us Now

+91 9606900005 / 04

For Enquiry

legacyiasacademy@gmail.com

Study flags high summer ozone levels in big cities

Key Findings: Summer 2025 Ozone (O) Crisis

  • Ozone levels exceeded prescribed limits for over ⅓ of summer days (March–May) in major cities.
  • Study by: Centre for Science and Environment (CSE)
  • Data Source: 80 ambient AQ monitoring stations in Mumbai, Kolkata, Bengaluru, Chennai, Hyderabad, Delhi.

Relevance : GS 3(Environment and Climate Change )

City-wise Breaches in Ozone Standards

CityDays O₃ exceeded standard (out of 92)Change vs 2024
Delhi33 days
Bengaluru45 days↑ 29%
Mumbai32 days↑ 42%
Chennai15 days↑ (from 0)
Kolkata22 days (↓ from 40)↓ 45%

Technical Insight

  • Standard Breach Definition: 8-hour average > 100 µg/m³, as per National Ambient Air Quality Standards (NAAQS).
  • O is not directly emitted, but forms via photochemical reaction (sunlight + NOx + VOCs).
  • Not monitored over 24-hour avg (unlike PM2.5/PM10) due to high reactivity.

Public Health Implications

  • Ground-level ozone:
    • Triggers respiratory illnesses, asthma, infections.
    • Reduces lung function, especially in children & elderly.
  • High temperatures + solar radiation → higher O₃ spikes in summers.

Expert View

“If unchecked, ozone pollution could become a serious public health crisis.” – Anumita Roychowdhury, CSE

Broader Pattern

  • Indian megacities now consistently exceed ozone norms in summers.
  • Northern India (e.g., Delhi) most affected due to:
    • Temperature inversion
    • Vehicular + industrial pollution

Ozone: Basics

  • Ozone (O) is a triatomic molecule made of three oxygen atoms.
  • Found in two layers:
    • Stratospheric ozone (good ozone): Forms the ozone layer, protects life by absorbing harmful UV-B radiation.
    • Tropospheric ozone (bad ozone): Acts as a pollutant and greenhouse gas, harmful to health and crops.

Ozone Layer & Its Importance

  • Located in the stratosphere (10–50 km altitude).
  • Absorbs 97–99% of the Sun’s medium-frequency ultraviolet light.
  • Prevents skin cancercataracts, and damage to plants/marine ecosystems.

Ozone Depletion

  • Caused by Ozone-Depleting Substances (ODS) like:
    • CFCs (chlorofluorocarbons)
    • Halons, Carbon tetrachloride, Methyl bromide
  • Major ozone hole detected over Antarctica.

Global Measures

  • Vienna Convention (1985): Framework for international cooperation.
  • Montreal Protocol (1987): Legally binding treaty to phase out ODS.
  • Kigali Amendment (2016): Added phase-down of HFCs (climate pollutants, not ODS).

July 2025
MTWTFSS
 123456
78910111213
14151617181920
21222324252627
28293031 
Categories