Delhi sixth most polluted city in country in October, Pg4.

Key Highlights:

• Delhi ranked as the sixth most polluted city in India in October with an average PM2.5 concentration of 107 µg/m3 [i.e., micrograms per cubic meter].
• Ghaziabad and Noida, both in the National Capital Region (NCR), secured the third and fourth spots respectively, in terms of pollution levels in October.
• Dharuhera in Haryana was the most polluted city in October, exceeding the National Ambient Air Quality Standard (NAAQS) limit on 77% of the days.
• In October, the number of cities with 'Good' Air Quality Index (AQI) decreased to 68 from 179 in September, while cities in the 'Satisfactory' category increased from 52 to 144.
• Shillong in Meghalaya was the cleanest city in India in October, with a monthly average PM2.5 of 10 µg/m3.

Top Polluted Cities in India (Oct 2025).png

Detailed Insights:

• The Centre for Research on Energy and Clean Air (CREA) report indicates a sharp deterioration in air quality across India, particularly in the Indo-Gangetic Plain (IGP) and the NCR.
• Despite stubble burning contributing to less than 6% of Delhi’s PM2.5 levels in October, the high pollution levels highlight the impact of year-round emission sources.
• The report emphasizes the need for long-term mitigation plans that go beyond short-term seasonal measures like the Graded Response Action Plan (GRAP).
• The megacities of Mumbai, Chennai, Kolkata, and Bengaluru had monthly average PM2.5 levels within the NAAQS limit in October, unlike Delhi.
• The analyst at CREA suggests prioritizing sector-specific emission cuts with clear accountability mechanisms to prevent the predictable surge in pollution during winter and festive seasons.
• The air quality in Delhi slightly improved, moving into the 'Poor' category with an overall AQI of 291 after hovering between 'Poor' and 'Very Poor' since Diwali.

Key Concepts Involved:

• PM2.5: Fine particulate matter with a diameter of 2.5 micrometers or less, a major air pollutant.
• NAAQS (National Ambient Air Quality Standards): Standards for ambient air quality set by the Central Pollution Control Board (CPCB) that needs to be achieved.
• AQI (Air Quality Index): A tool used to communicate air quality status to the public.
• GRAP (Graded Response Action Plan): A set of measures to be taken based on air quality levels.