Delhi's air quality has once again deteriorated, slipping back into the 'very poor' category after a brief respite of three days, with no immediate relief expected until December 13. This marks a concerning shift following a period of improved air quality, which saw the capital move into the 'poor' category.
On Thursday, the overall Air Quality Index (AQI) in Delhi reached 285, according to the Central Pollution Control Board (CPCB), nearing the 'very poor' threshold of 301. Several monitoring stations across the city have already recorded AQI levels above 300, placing them firmly in the 'very poor' zone. Anand Vihar and Delhi Cantonment, for instance, both registered an AQI of 302.
The CPCB defines an AQI between 201 and 300 as 'poor', while an AQI between 301 and 400 is classified as 'very poor'. AQI values between 0-50 are considered 'good', 51-100 'satisfactory', 101-200 'moderate', and 401-500 'severe'.
Wednesday saw a marginal improvement in Delhi's air quality due to stronger winds, with the 24-hour average AQI dropping to 259, a slight improvement from Tuesday's reading of 282. This improvement, however, proved short-lived as the air quality began to decline again. Prior to this brief improvement, Delhi residents endured nine consecutive days of 'very poor' air quality.
The Central Government's Air Quality Early Warning System forecasts that Delhi's air quality will remain in the 'very poor' category from December 11 to December 13. The outlook for the subsequent six days also indicates that the air quality is likely to persist in the 'very poor' category.
Contributing factors to Delhi's air pollution include weather conditions and pollutant accumulation. The predicted maximum mixing depth is expected to decrease from 1100 m on December 10 to 800 m on December 12, before rising slightly to 900 m on December 13. The ventilation index is also expected to decrease, with values of 4000 m2/s on December 11 and 800 m2/s on December 12 and 13. A ventilation index lower than 6000 m2/s, combined with average wind speeds less than 10 kmph, is unfavorable for the dispersion of pollutants.
The Commission for Air Quality Management (CAQM) has found that road dust continues to be a significant contributor to particulate matter levels in Delhi. In a recent inspection, 15 out of 79 road stretches were found to have "high dust intensity". The CAQM has emphasized the need for strengthened on-ground action, including regular mechanical sweeping, timely disposal of collected dust, and the deployment of water-sprinkling or dust-suppression systems.
The India Meteorological Department (IMD) has predicted partly foggy conditions for Delhi. Temperatures are expected to remain stable for the next two days, followed by a rise of 2–4°C over the subsequent three days.
