Will Ethiopian volcanic ash further impact poor Delhi AQI? Expert explains

As the massive ash cloud from Ethiopia's Hayli Gubbi made its way towards Delhi, the India Meteorological Department (IMD) on Tuesday assured that there would be "no impact" on the national capital's air quality. However, it noted that the movement will affect airline operations.

 

Mrutyunjaya Mohapatra, director-general of meteorology at IMD, told Business Standard, "The volcanic ash is moving at a height of 8.5 km to 15 km. So its impact will only be on aircraft operations. It has no impact on surface weather or air quality."

 

As reported earlier, the ash cloud from Hayli Gubbi, a long-silent volcano that erupted for the first time in nearly 12,000 years, entered India at around 10 pm on Monday.

Why Delhi faces high pollution

The troposphere (surface to ~12 km) is where all weather and pollution exist. But pollution does not fill the whole troposphere, it stays within the planetary boundary layer (PBL), the lowest few hundred metres to a few kilometres of the atmosphere. 

 

When the boundary layer is deep (1-3 km in summer), polluted air gets diluted. When it becomes shallow (100-300 m in winter), the same emissions stay concentrated near the surface.

 

In winter, the PBL height collapses, especially at night and early morning. This gives pollution very little vertical space, making the air quality index (AQI) spike in Delhi.

Delhi AQI already 'very poor'

The ash plume, which was released into the atmosphere during the volcano's eruption, consists of volcanic ash, sulphur dioxide and small particles of glass and rock, increasing the likelihood of hazy and darker skies than usual. This comes as Delhi's AQI has been in 'very poor' or 'severe' levels, with the city shrouded in haze and grey skies for nearly a month.

 

Delhi’s overall AQI stood at 362 at 8 am, placing it in the ‘very poor’ category on Tuesday, according to the Central Pollution Control Board (CPCB). Under CPCB classifications, AQI levels between 0–50 are considered “good”, 51–100 “satisfactory”, 101–200 “moderate”, 201–300 “poor”, 301–400 “very poor” and 401–500 “severe”.

Ash cloud to move away by evening

The IMD told PTI that the ash clouds are drifting towards China and will move away from India by 7.30 pm today.

 

According to the IMD, Hayli Gubbi erupted on Sunday, producing a large ash plume that rose to around 14 km (45,000 ft). The plume spread eastward across the Red Sea and towards the Arabian Peninsula and the Indian subcontinent.

Flight operations affected

Several leading airlines, including Air India and Akasa Air, cancelled some flights on Tuesday. In a post on X, Air India mentioned that a total of 11 flights were cancelled since Monday, when the ash plume was first seen entering the Indian airspace. It said, "The following Air India flights have been cancelled as we carry out precautionary checks on those aircraft which had flown over certain geographical locations after the Hayli Gubbi volcanic eruption."

 

Akasa Air also scrapped some scheduled flights in West Asia for destinations such as Jeddah, Kuwait, and Abu Dhabi scheduled during November 24-25. Earlier on Monday, IndiGo also cancelled six of its flights, a Hindustan Times report said, adding that several other flights were diverted.

 

Leading airlines, including IndiGo, Air India, SpiceJet, and Akasa Air, issued advisories on Monday regarding possible delays and cancellations.

 

According to PTI, IMD's Met Watch Offices in Mumbai, New Delhi, and Kolkata issued ICAO-standard Significant Meteorological Information (SIGMET) warnings to airports. The IMD said continuous monitoring of MET and ash advisories is used for flight planning, including adjustments to routing and fuel calculations based on alternate paths.

 

Flights over the region may face rerouting, longer flight times or holding patterns, IMD added.