Byrnihat emerges as the most polluted city
Byrnihat Tops Pollution List in 2025: A recent analysis by the Centre for Research on Energy and Clean Air (CREA) has placed Byrnihat, on the Assam-Meghalaya border, at the top of India’s most polluted cities in the first half of 2025. With an alarming average PM 2.5 concentration of 133 µg/m³, it exceeds the national safe limit more than three times. Delhi, India’s capital, came second with 87 µg/m³.
Air pollution breaching national safety limits
Out of the 293 cities monitored by Continuous Ambient Air Quality Monitoring Stations (CAAQMS), a total of 122 cities exceeded India’s safe PM 2.5 limits. This clearly signals the gravity of India’s urban air pollution crisis.
259 cities had already crossed the annual permissible PM 2.5 limit by June 2025, indicating long-term exposure for their residents. This data not only raises public health alarms but also underscores the limited effectiveness of current pollution control measures.
Understanding PM 2.5 and its dangers
PM 2.5 particles are fine inhalable particles with diameters that are 2.5 micrometres and smaller. They can penetrate deep into human lungs and enter the bloodstream.
Static GK fact: The National Ambient Air Quality Standards (NAAQS) of India prescribe a safe limit of 40 µg/m³ for PM 2.5.
These particles are linked to respiratory diseases, cardiovascular problems, stroke, and premature deaths. Children, the elderly, and individuals with pre-existing conditions are at heightened risk.
Cities under the red zone
Besides Byrnihat and Delhi, cities such as Hajipur (Bihar), Ghaziabad (Uttar Pradesh), Gurgaon (Haryana), Sasaram, Rajgir, and Patna (Bihar) also ranked high in the pollution index. Industrial towns like Talcher and Rourkela (Odisha) were also in the top 10, primarily due to coal-based industries.
Static GK Tip: Talcher is one of the major coal-producing towns in India and hosts multiple thermal power plants.
National Clean Air Programme progress
India’s National Clean Air Programme (NCAP) covers 131 non-attainment cities, aiming to reduce PM concentrations by 20–30% by 2026. Out of these, 98 cities have CAAQMS infrastructure in place, but the implementation gap remains wide.
Static GK fact: NCAP was launched in 2019 under the Ministry of Environment, Forest and Climate Change (MoEFCC).
Cleanest Indian cities show the way
Amidst the gloom, a few cities have shown promising air quality figures. Aizawl (Mizoram) emerged as the cleanest city, with PM 2.5 at 8 µg/m³ — marginally above the WHO safe limit of 5 µg/m³.
Other clean cities included:
- Tirupur and Tirunelveli in Tamil Nadu
- Imphal (Manipur)
- Maihar (Madhya Pradesh)
- Chamrajanagar and Chikkamagaluru (Karnataka)
- Bareilly and Vrindavan (Uttar Pradesh)
These cities offer case studies for pollution control and urban planning.
Static Usthadian Current Affairs Table
Byrnihat Tops Pollution List in 2025:
| Topic | Detail |
| Byrnihat PM 2.5 Level | 133 µg/m³ |
| Delhi PM 2.5 Level | 87 µg/m³ |
| National Safe Limit (India) | 40 µg/m³ |
| WHO Safe Limit for PM 2.5 | 5 µg/m³ |
| Total Cities Monitored (2025) | 293 |
| Cities Exceeding Safe Limits | 122 |
| Cities Crossing Annual Limit by June | 259 |
| Cleanest City in India | Aizawl (8 µg/m³) |
| NCAP Launch Year | 2019 |
| Cities Covered Under NCAP | 131 |
