A report by Centre for Research on Energy and Clean Air (CREA), based on data from government-run Continuous Ambient Air Quality Monitoring Stations (CAAQMS) across 293 cities, found Byrnihat, located on the Assam-Meghalaya border, to be the most polluted city in India during the first half of 2025 (January–June).
Key Findings from CREA Report
- Byrnihat recorded PM2.5 concentration of 133 µg/m³, the highest among all cities.
- Delhi stood second with PM2.5 at 87 µg/m³, followed by:
- Hajipur (Bihar)
- Ghaziabad (Uttar Pradesh)
- Gurgaon (Haryana)
- PM2.5 pollutants are fine inhalable particles (<2.5 microns) that penetrate deep into lungs and bloodstream, causing respiratory and cardiovascular diseases.
- Delhi’s air quality: 63 days were in ‘moderate’ category (PM2.5: 61–90 µg/m³); 29 days in ‘very poor’.
Top 10 Most Polluted Cities (Till June 2025)
Besides Byrnihat and Delhi, other cities include:
- Sasaram, Patna, Rajgir (Bihar)
- Talcher, Rourkela (Odisha)
Notably, the same 10 cities were among the most polluted during the same period in 2024 as well.
Top Cleanest Cities in H1 2025
- Aizawl (Mizoram) was the cleanest city, with PM2.5 average at 8 µg/m³.
- WHO’s safe limit is 5 µg/m³.
- Other clean cities: Tirupur, Tirunelveli (Tamil Nadu), Bareilly, Vrindavan (UP), Maihar (MP), Imphal (Manipur), Chamrajanagar, Chikkamagaluru (Karnataka)
Compliance Insights from CAAMS Network
- Among 131 cities under NCAP, 98 have CAAMS; of these, 55 cities exceeded the national PM2.5 standard (40 µg/m³).
- Among 141 non-NCAP cities, 67 cities exceeded the national standard.
- 259 out of 293 monitored cities overshot the annual PM2.5 threshold by mid-2025, indicating early annual exceedance.
About Continuous Ambient Air Quality Monitoring Stations (CAAQMS)
- Real-time monitoring of pollutants like PM2.5, PM10, SO₂, NO₂, CO, O₃, VOCs.
- Uses IoT-based automated transmission of data.
- Enables AI-based analysis and national air quality forecasting.
- Crucial for implementation and evaluation of the National Clean Air Programme (NCAP).
National Clean Air Programme (NCAP)
- Launched: January 2019 by the Ministry of Environment, Forest and Climate Change (MoEFCC)
- Initial goal: 20–30% reduction in PM levels by 2024 from 2017 levels.
- Revised target (2023): 40% reduction by 2026.
Key Components:
- Clean Air Action Plans (CAAPs) in non-attainment cities.
- Strengthening monitoring networks – target of:
- 1,500 manual stations by 2024 (only 931 operational as of Dec 2023)
- 150 CAAQMS – surpassed with 531 operational by 2023.
- Public awareness and pollution forecasting systems
- Only Delhi has a fully functional forecasting system.
Funding Status:
- Total Allocation: ₹10,422.73 crore
- Allocation to 82 non-attainment cities: ₹1,253 crore
- Utilisation (till Nov 2023): Only ₹498 crore (~40%)
Significance
- Environmental governance: Highlights gaps between policy goals and implementation.
- Health linkage: High PM2.5 exposure causes chronic diseases—important for Social Justice & Public Health topics.
- State-specific importance: Focus on NE India (Byrnihat), Bihar, Odisha—often neglected in national air pollution discourse.
- Urban Planning and Policy: Data-driven environmental policy is critical for Smart Cities & Sustainable Development Goals (SDGs).
Key Facts
- PM2.5 vs PM10:
- PM2.5: Fine particles <2.5 microns, enter lungs/bloodstream.
- PM10: Particles <10 microns, can cause throat and respiratory irritation.
- WHO Guidelines (2021): Annual average PM2.5 limit = 5 µg/m³
- National Ambient Air Quality Standards (NAAQS) (India): PM2.5 = 40 µg/m³
- Air Quality Index (AQI) is measured on six pollutants: PM2.5, PM10, SO2, NO2, CO, and O3.
- National Clean Air Programme (NCAP) was launched in 2019 to improve air quality by 20–30% by 2024 in non-attainment cities.