New Delhi – Delhi air quality AQI deteriorated significantly on Sunday, recording the season’s worst pollution levels and raising concerns about public health as the capital enters its most polluted period of the year. With forecasts predicting the first ‘severe’ air day of 2025 this week, residents are bracing for hazardous atmospheric conditions that characterize Delhi’s winter months.
Season High Recorded on Sunday
The Delhi air quality AQI stayed in the ‘very poor’ category throughout Sunday, touching a season high of 388 at 10 am. This represents one of the worst pollution days recorded since the beginning of the current season. At 4 pm, when the Central Pollution Control Board (CPCB) released its daily national bulletin, the average Delhi air quality AQI had marginally improved to 366 as winds picked up speed during the day.
Despite this slight improvement in the city-wide average, at least five individual active ambient air quality monitoring stations recorded readings in the ‘severe’ category, indicating highly localized pockets of dangerous pollution levels across the capital.
Understanding AQI Categories
The CPCB classifies the Delhi air quality AQI using a comprehensive scale to help citizens understand pollution severity. An AQI between 0-50 is classified as “good”, 51-100 as “satisfactory”, 101-200 as “moderate”, 201-300 as “poor”, 301-400 as “very poor”, and readings over 400 as “severe”. The severe category represents the most hazardous air quality conditions, posing serious health risks to all residents, particularly vulnerable populations.
Severe Air Day Expected Tuesday
According to the Centre’s Air Quality Early Warning System (EWS) daily bulletin, the Delhi air quality AQI trajectory over the coming days follows a concerning pattern. “Delhi’s air quality is very likely to be in the ‘very poor’ category from Sunday till Monday. The air quality is very likely to be in the ‘severe’ category on Tuesday, before once again returning to ‘very poor’ on Wednesday,” the bulletin stated.
If this forecast materializes, Tuesday will mark the capital’s first official ‘severe’ air day of 2025. The last time the Delhi air quality AQI reached severe levels was on December 23, 2024, when it was recorded at 406.
Stations Recording Severe Levels
On Sunday at 4 pm, of the 39 active ambient air quality monitoring stations across Delhi, five had already entered the ‘severe’ category. According to CPCB data, Burari recorded an AQI of 404, Chandni Chowk registered 404, RK Puram showed 401, Vivek Vihar recorded 402, and Wazirpur registered the highest reading at 418. Another 30 stations recorded readings in the ‘very poor’ category, indicating widespread pollution across the capital.
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Most Polluted Time of Year
Long-term Delhi air quality AQI trends reveal that the capital has now entered its most polluted period. A Delhi Pollution Control Committee (DPCC) assessment of CPCB data between 2018 and 2022 showed that November 1-15 consistently records the highest AQI readings in the entire year. This period is followed by December 16-31, which has the second-highest average pollution levels over a 15-day period.
A 2019 IIT-Delhi study corroborated these findings, noting that the first pollution peak typically occurs between October 29 and November 4, followed by a second peak between December 30 and January 5. The current Delhi air quality AQI deterioration aligns perfectly with these established patterns.
Meteorological Factors
Mahesh Palawat, vice president at Skymet meteorology, explained that atmospheric conditions were unfavorable for dispersion of pollutants, leading to gradual accumulation that worsened the Delhi air quality AQI. “Winds picked up—touching around 10 km/hr during the day on Sunday, which led to an improvement in the AQI. Otherwise, we were mostly seeing calm winds,” he stated.
The wind direction remained variable throughout the day, except during the afternoon when it shifted to westerly and northwesterly—conditions favorable for transporting stubble smoke to Delhi. Despite the influence of a western disturbance on the region on November 4 and 5, Delhi is not expected to receive rain, which typically helps improve air quality. “It will impact the hills. Over Delhi, we will only see some cloudiness,” Palawat added.
Dramatic Oscillations
The Delhi air quality AQI has witnessed dramatic oscillations over recent days, registering 373 on October 30, improving significantly to 218 on October 31, deteriorating again to 303 on November 1, and reaching 366 on November 2. The Delhi government has defended itself against allegations of data manipulation, emphasizing that AQI monitoring stations are “tamper-free.”
Pollution Source Analysis
Data from the Decision Support System (DSS) revealed that stubble burning contribution to the Delhi air quality AQI was relatively low at 3.5% on Sunday, dropping from 9%—a season-high—on Saturday. This year’s delayed harvesting season has kept farm fires relatively low compared to previous years when stubble burning peaked at up to 35% contribution during the first week of November.
The transport sector emerged as the biggest contributor to Delhi’s PM2.5 pollution at 18.13%, followed by 11.2% from Jhajjar and 4.5% from Delhi’s residential sector. Approximately 36.8% came from unaccounted sources outside Delhi, highlighting the regional nature of the pollution crisis.
Weather Conditions
Delhi’s minimum temperature stood at 16.8°C, two degrees above normal, while the maximum reached 30.7°C, around normal levels. The minimum temperature is expected to touch and possibly dip below 15°C after November 7, while the maximum is likely to oscillate between 29-31°C until Wednesday.
As the Delhi air quality AQI continues deteriorating, health experts advise residents to limit outdoor activities and use protective measures.
