New Delhi: Delhi ranked as the most polluted among 33 states and Union territories with an annual mean PM2.5 concentration of 101 micrograms per cubic metre, 2.5 times the Indian standard and 20 times the WHO guideline, according to a new satellite-based analysis.
The report by the independent research organisation Centre for Research on Energy and Clean Air said Chandigarh recorded the second-highest annual average PM2.5 level at 70 micrograms per cubic metre during the study period from March 2024 to February 2025, followed by Haryana at 63 and Tripura at 62.
Assam (60), Bihar (59), West Bengal (57), Punjab (56), Meghalaya (53) and Nagaland (52) also exceeded the national standard.
Overall, 447 of the 749 districts (60 per cent) analysed breached the National Ambient Air Quality Standard (NAAQS) for annual PM2.5 of 40 micrograms per cubic metre.
The most polluted districts are heavily concentrated in a few states, the analysis showed.
Delhi (11 districts) and Assam (11 districts) together accounted for nearly half of the top 50, followed by Bihar (7) and Haryana (7). Other contributors include Uttar Pradesh (4), Tripura (3), Rajasthan (2) and West Bengal (2). In several states, all monitored districts exceeded the NAAQS. These include Delhi, Assam, Punjab, Haryana, Chandigarh, Himachal Pradesh, Meghalaya, Tripura and Jammu and Kashmir.
Several others showed a large majority of districts breaching the standard, such as Bihar (37 of 38), West Bengal (22 of 23), Gujarat (32 of 33), Nagaland (11 of 12), Rajasthan (30 of 33) and Jharkhand (21 of 24).
Ladakh, Andaman and Nicobar Islands, and Lakshadweep were excluded from the analysis due to insufficient ground monitoring data during the study period.
At least 7 international flights were cancelled and more than 10 overseas flights delayed at the Delhi airport on Tuesday as ash plumes from the volcanic eruption in Ethiopia impacted airlines' operations.
Air India has cancelled 13 flights since Monday.
Ash clouds from the recent eruption of the Hayli Gubbi volcano in Ethiopia are impacting flight operations, and there are reports suggesting that clouds are drifting towards the western parts of India.An official said 7 international flights, including arrivals and departures, were cancelled and 12 international flights were delayed at the Delhi airport due to the impact of the volcanic ash plumes. Hayli Gubbi, a shield volcano located in Ethiopia's Afar region, erupted on Sunday, producing a large ash plume rising to approximately 14 km (45,000 ft) in altitude and spreading eastward across the Red Sea. Forecast models indicated ash influence over Gujarat, Delhi-NCR, Rajasthan, Punjab and Haryana on Tuesday, the IMD said. The air quality is expected to remain in the 'very poor' category over the next few days.