Delhi’s air quality crisis deepened for the fourth consecutive day on Tuesday, staying firmly in the “very poor” category. The 24-hour rolling average Air Quality Index (AQI) was recorded at 311 at 9 am, a slight increase from the previous day’s official CPCB reading of 309. The situation is on the verge of further deterioration as a meteorological phenomenon threatens to completely still the winds that disperse pollutants.
Meteorological Shift: Western Disturbance to Stifle Winds
The primary cause for the expected spike in pollution is a western disturbance, a weather system that is forecast to bring about a sharp reduction in wind speed:
- Calm Conditions Forecast: Meteorological experts predict that wind speed will drop sharply on Tuesday and become almost calm on Wednesday. This sudden lack of air movement will trap pollutants close to the ground.
- Worsening Prediction: Private forecaster Skymet Weather highlighted that the combination of near-calm winds and increased moisture will lead to a haze and a significant rise in pollution. Another meteorologist warned that this disturbance will negatively impact the AQI, potentially creating a fresh layer of smog over November 4 and 5.
- Official Outlook: The Early Warning System (EWS) for Delhi, managed by the Indian Institute of Tropical Meteorology (IITM), forecasts the AQI will remain “very poor” on both Tuesday and Wednesday. The overall outlook is that the AQI will likely stay “very poor” until Thursday and for the subsequent six days.
The current situation is precarious, as Delhi has yet to record a “severe” air day since December 23, 2024 (when the AQI hit 406).
Ground Reality: ‘Severe’ Spikes in Local Areas
Despite the city’s overall average being “very poor,” data from the CPCB’s Sameer app shows that several localities have already crossed the threshold into the most dangerous category:
- Severe Zones (AQI > 400): At least four of the 38 active stations were recorded in the “severe” zone, including Alipur (421), Anand Vihar (412), Bawana (402), and Wazirpur (407).
- Moderate Zones: Meanwhile, three stations, including IGI airport (193), Lodhi Road (153), and Aurobindo Marg (146), remained in the “moderate” range.
- Data Reliability Concerns: Concerns about data integrity were raised after it was noted that some busy locations, such as ITO, showed artificially low averages due to several hours of missing data in the app.
The CPCB’s official AQI classifications are: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), and Severe (>400).
Stubble Burning and Future Relief
- Low Stubble Contribution: The estimated contribution of stubble burning to Delhi’s PM 2.5 on Sunday was a relatively low 3.5%, down from a season-high of 9% on Saturday. Historically, this contribution peaks at up to 35% in early November.