Ethiopian Volcanic Ash Delhi Air Quality
- Teh India Meteorological Department (IMD) assured residents of Delhi that the ash cloud from Ethiopia's Hayli Gubbi volcano would not impact the city's air quality, despite its trajectory...
- Mrutyunjaya Mohapatra, director-general of meteorology at IMD, explained that the volcanic ash is traveling at an altitude of 8.5 to 15 kilometers.
- Understanding why Delhi frequently experiences poor air quality requires understanding the troposphere and, crucially, the Planetary Boundary Layer (PBL).
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Hayli Gubbi Volcano Ash Cloud: No Impact on Delhi Air Quality, but Airline Operations Affected
What Happened?
Teh India Meteorological Department (IMD) assured residents of Delhi that the ash cloud from Ethiopia‘s Hayli Gubbi volcano would not impact the city’s air quality, despite its trajectory towards the national capital. The ash cloud, originating from the volcano’s first eruption in nearly 12,000 years, entered India around 10 pm on Monday. However, the IMD cautioned that the ash cloud will affect airline operations.
Mrutyunjaya Mohapatra, director-general of meteorology at IMD, explained that the volcanic ash is traveling at an altitude of 8.5 to 15 kilometers. This height means the impact will be limited to aircraft operations and will not affect surface weather or air quality.
Why Delhi Faces High Pollution - A Primer on the Planetary Boundary Layer
Understanding why Delhi frequently experiences poor air quality requires understanding the troposphere and, crucially, the Planetary Boundary Layer (PBL). The troposphere, extending from the surface to approximately 12 kilometers, is where all weather and pollution reside. However, pollution doesn’t uniformly fill the troposphere; it concentrates within the PBL, the lowest few hundred meters to a few kilometers of the atmosphere.
The depth of the PBL significantly influences air quality. A deep PBL (1-3 km in summer) allows for greater dilution of pollutants. Conversely, a shallow PBL (100-300 m in winter) traps emissions near the surface, leading to higher concentrations.
During winter, the PBL height collapses, particularly at night and in the early morning. This limited vertical space exacerbates pollution, causing the Air Quality Index (AQI) to spike in Delhi.
Delhi AQI Already ‘Very Poor’
The ash plume released during the hayli Gubbi eruption contains volcanic ash, sulphur dioxide, and small particles of glass and rock. This composition increases the likelihood of hazy and darker skies.While the IMD states the ash won’t worsen surface air quality, Delhi’s AQI was already categorized as ‘very poor’ prior to the ash cloud’s arrival, indicating pre-existing pollution issues.
| AQI Category | PM2.5 Concentration (µg/m³) | Health Implications |
|---|---|---|
| Good | 0-50 | Minimal risk |
| moderate | 51-100 | Acceptable for most; sensitive groups may experience minor irritation |
| Poor | 101-150 | May cause breathing discomfort to people with lung disease |
| very Poor | 151-200 | May cause respiratory illness; avoid prolonged exposure |
| Severe | 201-300 | Affects healthy people; serious health risks |
| Hazardous | 301+ | severe health risks; avoid all outdoor activity |