By Manoj Kumar N and Nandikesh Sivalingam
Key highlights
- Compliance: In September 2024, 260 out of 264 cities with more than 80% of the days with CAAQMS data available, recorded PM2.5 concentrations below India’s NAAQS of 60 µg/m³. 44 cities complied with the WHO’s daily safe guideline concentration of 15 µg/m³.
- NCAP cities: The monthly average PM2.5 levels in 79 NCAP cities (out of 96 cities with more than 80% of days with data) surpassed the WHO’s daily guideline for PM2.5, while 95 cities met India’s daily NAAQS.
- Non-NCAP cities: Among the 149 non-NCAP cities with over 80% of days with CAAQMS data, 98 cities reported monthly average PM2.5 levels above the WHO daily guideline. All 149 cities adhered to the daily NAAQS.
- The surge in Indian cities meeting NAAQS and WHO standards is a direct result of the heavy August rains.
- AQI category: In September 2024, the number of cities with “Good (0-30 µg/m³)” air quality dropped to 201 from 218 in August. The number of cities with “Satisfactory (31-60 µg/m³)” air quality increased from 26 to 59. Additionally, 4 cities experienced “Moderate (61-90 µg/m³)” air quality in September, compared to just 1 city in August. Overall, September saw a slow transition from the “Good” to the “Satisfactory” category, largely attributable to shifts observed in the states of Haryana, Uttar Pradesh, and Rajasthan within the Indo-Gangetic Plain.
- Delhi: Delhi recorded an average concentration of 43 µg/m³ in September, with 9 days in the “Good” category, 16 days in the “Satisfactory” category, 4 days in the “Moderate” category, and 1 day in the “Very Poor (121-250)” category. This is higher than August’s average of 27 µg/m³, when there were 24 days in the “Good” category and 7 days in the “Satisfactory” category.
- Cleanest city: Aizawl, in the state of Mizoram, was the cleanest city in India during September, with monthly average PM2.5 of 3 µg/m³.
- Most polluted city: Byrnihat in Assam/Meghalaya ranked as the most polluted city in India in September 2024, recording a monthly average PM2.5 concentration of 73 µg/m³, surpassing the daily National Ambient Air Quality Standards (NAAQS of 60 µg/m³) 57% of the days in the month.
- Frequency in top 10 polluted cities: A total of 67 cities were featured in the daily top 10 most polluted cities list in September 2024. Of these, 26 cities made an appearance at least five times over the 30-day period, topped by Byrnihat in Assam/Meghalaya, which featured the most times (17 days), followed by Jalna (17 days), Sri Ganganagar (15 days), Mandi Gobindgarh (14 days), Nandesari (13 days), Ghaziabad (12 days), and Gummidipoondi (11 days).
- NCAP: Only 25 out of the 67 cities featured in the daily top 10 most polluted cities list during September 2024 are part of the National Clean Air Programme (NCAP). The remaining 43 have no action plan to reduce hazardous air pollution concentrations.
- Megacities: With the exception of Delhi, all other megacities, such as Chennai, Mumbai, Kolkata, and Bangalore, saw all their days in September falling within the ‘Good’ and ‘Satisfactory’ category.
- Monitoring infrastructure: One new continuous ambient air quality monitoring stations (CAAQMS) was installed in September 2024 at Indore. This increased the national total to 551 stations.
Monthly ambient air quality snapshot for India: September 2024
Monthly ambient air quality trends in India: September 2024 air quality snapshot (pdf version)
Press release – Monthly ambient air quality trends in India: September 2024 air quality snapshot
Data sources
Ambient air quality data recorded by Continuous Ambient Air Quality Monitoring Stations (CAAQMS) is downloaded from the ‘Central Control Room for Air Quality Management – All India‘ dashboard operated by the Central Pollution Control Board (CPCB).