Delhi’s Air Quality Plunges to ‘Poor’ Ahead of Diwali
Delhi’s familiar smog season has officially begun. The city’s air quality deteriorated into the ‘poor’ category for the first time this season on Tuesday, just over a week before the major festival of Diwali.
Data from the Central Pollution Control Board (CPCB) showed the city’s average Air Quality Index (AQI) hitting 202 (poor) at 11 am. This marks the first time Delhi has recorded an AQI in the 200-plus range since June 11, when the air quality stood at 245 (poor). The visible impact of this deterioration was already evident, with a thin layer of smog reportedly engulfing areas like Kartavya Path.
Forecast: No Relief Expected
The grim outlook suggests the situation will worsen. The Centre’s Air Quality Early Warning System (EWS) for Delhi has forecasted no immediate relief, with the AQI likely to breach the ‘very poor’ category around or after Diwali.
According to the EWS bulletin released on Monday:
- October 14-16: Delhi’s air quality is very likely to remain in the ‘poor’ (201−300) category.
- Subsequent Six Days: The air quality outlook shows a further decline, likely fluctuating between the ‘poor’ (201−300) and ‘very poor’ (301−400) categories.
Why the Spike? Transport and Weather Factors
Experts attribute the initial spike in pollution primarily to changing weather conditions. Mahesh Palawat, Vice President at Skymet Meteorology, noted that wind speeds are currently quite low, oscillating between 6−10 km/hr.
“The wind direction is westerly to northwesterly, and there will be marginal stubble intrusion,” Palawat explained, adding that with low wind speed and direction expected to persist, no significant weather change is predicted to aid in pollutant dispersion.
The annual worsening of the AQI in October is a cyclical event, typically triggered by:
- The withdrawal of the southwest monsoon.
- A dip in air temperature and wind speed (which traps pollutants).
- The start of stubble burning in northwest India.
- Emissions from firecrackers during the festival season.
Source Contribution: Local Traffic Leads the Charge
Analysis from the Decision Support System (DSS)—a model that estimates the contribution of various sources to Delhi’s PM 2.5 levels—pinpointed the biggest polluters on Monday:
- Top Contributor: The city’s transport sector accounted for the highest share at 19.6%.
- Neighbouring Areas: This was followed by contributions from Jhajjar (9.8%) and Sonipat (6.1%).
- Stubble Burning: While often cited, the contribution of stubble burning to Delhi’s total PM 2.5 load was minimal on Monday at only around 0.62%, a marginal increase from 0.24% on Sunday. The forecast for Tuesday anticipated a 0.49% contribution from farm fires.
The CPCB’s official AQI scale classifies air quality as: 0−50 ‘good,’ 51−100 ‘satisfactory,’ 101−200 ‘moderate,’ 201−300 ‘poor,’ 301−400 ‘very poor,’ and 401−500 ‘severe.’ Delhi’s air is now firmly in the range where it begins to seriously affect vulnerable groups and cause discomfort for others.