Ash cloud sweeps across Indian sky; IMD says no pollution risk for Delhi-NCR

Volcanic ash from Ethiopia's eruption disrupted flights across India but had minimal impact on air quality, exiting the country by Tuesday evening.

The vast windborne cloud of volcanic ash released during Monday’s eruption in Ethiopia swept across the Indian landmass on Tuesday, passing over Gujarat, Rajasthan, NCR, Uttar Pradesh, Bihar and the northeast before advancing toward China, the India Meteorological Department (IMD) said. The plume traced an extraordinary high-altitude trajectory across West Asia and India, but its impact on Delhi’s already toxic air remained negligible, officials said.

Airlines including Air India and Akasa Air cancelled services after warnings from aviation authorities.

Aviation, however, bore the brunt. As on Monday, several flights were cancelled, delayed or diverted as a precaution, with airlines and aviation authorities responding to fast-changing upper-air conditions.

Carried by strong westerly winds in the upper atmosphere, the plume initially travelled across Yemen, Oman and the Arabian Sea before entering Indian airspace over the country’s western coast in Gujarat and Rajasthan around 6.30pm on Monday. By 11pm, its outer edge had reached Delhi at altitudes between 9km and 15km, continuing its rapid eastward sweep through Tuesday.

IMD said that, as of 10:30 pm, satellite imagery showed the ash plume had completely exited India. “These ash particles are moving at 8–15km above the surface, so the main impact was on aviation operations over Delhi, Kolkata and Mumbai. There was no impact on the surface or the weather. There is no concern of exposure because at that height wind speeds are 100-150 kmph – the particles move away before they can settle,” said IMD director general M Mohapatra.

By 8.30pm Tuesday, IMD said the plume had largely exited India, except for a thinning tail over the northeast.

Flight operations across multiple sectors were disrupted. Airlines began cancelling flights late Monday, after the Directorate General of Civil Aviation issued an advisory warning of possible hazards to aircraft engines. Key air routes across northwest India were affected. IndiGo’s Kannur-Abu Dhabi service was diverted to Ahmedabad to avoid the plume.

Air India, which cancelled seven flights on Monday, scrapped four more on Tuesday, including Chennai-Mumbai and Hyderabad-Delhi services. In a statement, the airline said the cancellations were precautionary. “We are carrying out checks on aircraft that flew over certain geographical locations after the Hayli Gubbi volcanic eruption,” it said on X.

At Delhi’s IGI Airport, seven international flights were cancelled and 12 delayed by 6pm Tuesday, officials said.

Akasa Air cancelled its international services to and from Jeddah, Kuwait and Abu Dhabi on November 24 and 25, affecting several Gulf-bound passengers.

The Union ministry of civil aviation said it was coordinating closely with air traffic control, IMD, airlines and global aviation agencies. “AAI has issued the necessary NOTAM and all affected flights have been kept informed… Operations remain smooth, with only a few flights rerouted or descended as a precaution,” it said on X.

Despite initial fears that the ash cloud might worsen pollution in Delhi, its presence was barely detectable at ground level. Delhi’s AQI was 370 at 11pm Monday when the plume first skimmed the city. By 4pm Tuesday, it had dipped to 353, according to the Central Pollution Control Board’s national bulletin.

HT’s analysis of real-time monitoring data showed only minor, inconsistent fluctuations. At Mandir Marg, PM2.5 rose from 173 µg/m³ at 11pm to 185 µg/m³ at midnight, then touched 218 µg/m³ at 2am. SO₂ levels showed a brief rise from 41.3 µg/m³ to 61.8 µg/m³.

At Anand Vihar, PM2.5 increased from 328 µg/m³ to 382 µg/m³ at midnight, while SO₂ rose slightly from 9.2 µg/m³ to 12.9 µg/m³. At Punjabi Bagh, PM2.5 climbed from 306 µg/m³ to 345 µg/m³ even as SO₂ dipped-showing no clear pattern attributable to the plume.

Prof Abhineety Goel, Faculty of Environmental Studies at FLAME University, said the ash cloud was travelling at elevations between 27,000 and 50,000 feet—far above the tropospheric layer where Delhi’s pollution accumulates. “Most pollutants that deteriorate Delhi’s air are confined to the lower layers of the atmosphere. This ash cloud is in the stratosphere. Although heavier particles may eventually descend, any deposition is more likely to affect soil, vegetation or water bodies than immediate air quality,” she said. The primary advisories, she added, were therefore focused on aviation safety rather than public health.

“There is a well-marked low-pressure area over Malaysia and adjoining Strait of Malacca which intensified into depression over strait of Malacca. There is also a low-pressure area over southwest Bay of Bengal and adjoining areas of South Sri Lanka and Equatorial Indian Ocean. Heavy rainfall is likely over Tamil Nadu till November 30; over Kerala and Mahe on November 26; coastal Andhra Pradesh, Yanam and Rayalaseema during November 29 to December 1; Andaman & Nicobar Islands till November 29 with very heavy rainfall over Tamil Nadu during November 28 to 30, Andaman & Nicobar Islands during November 26 and 27, Coastal Andhra Pradesh & Yanam and Rayalaseema on November 30,” IMD said in a statement.

“We can expect widespread rain over parts of Peninsular India,” Mohapatra said.

This article has insights by Prof. Abhineety Goyal, Faculty of Environmental Studies, FLAME University.