The air quality in Delhi has experienced a troubling shift, returning to the 'severe' category, with an alarming Air Quality Index (AQI) recorded at 427 as of 7 AM on Sunday. This deterioration in air quality follows a temporary improvement that had seen the AQI fall within the 'very poor' range earlier.

As reported by the Central Pollution Control Board (CPCB), an AQI that falls between 401 and 450 is classified as 'severe'. The predominant pollutant contributing to this dire situation is PM2.5, a fine particulate matter known for its harmful effects on health.

On top of the hazardous air quality, the residents of Delhi are also grappling with extremely cold weather conditions, compounded by a thick layer of smog that enveloped the city on Sunday morning.

The meteorological data from the India Meteorological Department (IMD) indicates that the minimum temperature at 7 AM was registered at 8 degrees Celsius, which is anticipated to be the day’s low. Meanwhile, a maximum temperature around 24 degrees Celsius is expected.

As the air quality continues to decline, vulnerable populations, including the homeless, can be seen seeking refuge in shelters and tents throughout the city during this chilling winter season.

Delhi has witnessed a gradual decline in air quality since the previous Sunday, primarily attributed to a decrease in wind speed, marking this as the most significant deterioration since December 2021.

True to the IMD’s predictions, the AQI for Sunday fell back into the 'severe' category. The 24-hour average AQI on Saturday was reported at 370, which is categorized as 'very poor' by the CPCB's daily metrics. Furthermore, the air quality had exceeded the 400 threshold on both Thursday and Friday, also classifying it as 'severe'.

The following are the AQI readings from various areas in Delhi on Sunday morning: Anand Vihar: 427, Ashok Vihar: 430, Bawana: 432, Burari Crossing: 410, Dwarka Sector 8: 429, IGI Airport (T3): 372, ITO: 384, Jahangirpuri: 441, Major Dhyan Chand National Stadium: 382, Mundka: 428, Nehru Nagar: 430, Okhla Phase 2: 390, Patparganj: 402, RK Puram: 408, Vivek Vihar: 419, and Wazirpur: 434.

According to CPCB standards, the AQI classification ranges from 0-50 being 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor', 401-450 'severe', and anything above 450 labeled as 'severe plus'. With the AQI currently in the 401-450 range, the city is subject to restrictions under Stage 3 (severe) of the Graded Response Action Plan (GRAP).

Health professionals have strongly advised the public to limit outdoor activities wherever possible, especially for vulnerable groups like seniors, children, and individuals with pre-existing respiratory conditions, given the current air quality crisis.

Looking ahead, the weather forecast for Monday, December 23 anticipates light rain or drizzle with the minimum temperature expected to drop to around 7 degrees and a maximum of 22 degrees Celsius. As Christmas approaches, dense and moderate fog is predicted for Christmas Eve and Christmas Day, with minimum temperatures expected to hover around 8 degrees Celsius on both days.