Chennai stood out for its severe pollution surge during Deepavali, Pg9

Key Highlights:

• Chennai recorded its highest PM10 levels of the year around Deepavali 2025, reaching over 900.
• Chennai's PM10 concentrations spiked only around Deepavali, unlike cities with consistently high pollution.
• NOₓ and SO₂ levels in Chennai reached their annual peaks during Deepavali.
• Persistent rain caused pollution levels in Chennai to drop sharply after peaking.

Detailed Insights:

• Many Indian cities, including Chennai, Hyderabad, and Ahmedabad, experienced high PM10 levels during Deepavali.
• Ahmedabad recorded the highest pollution levels overall this year, but unlike Chennai, it experiences high pollution throughout the year.
• Besides PM10 and PM2.5, levels of NH₃, NO, NO₂, and SO₂ also spiked in Chennai during Deepavali.
• The air pollution surge in Chennai and Hyderabad was particularly noticeable, but Chennai's pollution decreased rapidly due to rain.

Scientific/Technical Concepts Involved:

• PM10: Particulate matter with a diameter of 10 micrometers or less, posing respiratory health risks.
• NOₓ: A mixture of nitrogen oxides, primarily nitric oxide (NO) and nitrogen dioxide (NO₂), contributing to smog and acid rain.
• SO₂: Sulfur dioxide, a pollutant gas that can cause respiratory problems and contribute to acid rain.