Delhi-NCR air pollution: December on track to be dirtiest in 8 yrs amid severe fog, ITO records worst AQI

Delhi is facing another stretch of poor air quality and persistent fog, with December already recording three severe air days and the month's average air quality index (AQI) rising to critical levels. The capital experienced a 24-day streak of very poor air in November, including three severe days mid-month. 

On Saturday, the national capital was shrouded in a thick layer of noxious smog, with the overall AQI standing at 380 at around 7 am, falling into the 'very poor' category.

AQI across various parts of Delhi (as of 7 am on December 20)

• ITO -- 429
• Sarai Kale Khan -- 428
• Anand Vihar -- 428
• Akshardham -- 420
• Ashok Vihar -- 407
• Rao Tularam Marg -- 403
• Barapullah flyover -- 380

Persistent pollution coincides with dense fog and a lack of rainfall this December, as recorded at the Safdarjung weather station. The absence of rain prevents pollutants from being cleared, worsening air quality. On Friday, dense fog caused widespread travel disruption, with over 700 flights affected and at least 177 cancelled, as conditions are forecast to deteriorate over the weekend.

Previously, the India Meteorological Department (IMD) issued an orange alert for fog on Saturday. An IMD official said, "Dense to very dense fog is expected to form at several places across the city in the early hours of Saturday. At night, a shallow fog or mist might be observed."

Despite enforcement drives, Delhi's air quality marked its ninth consecutive day of very poor or severe pollution. Authorities issued thousands of challans, disrupting commuters across the National Capital Region, reinforcing the Supreme Court's earlier description of a "total failure" of reactive pollution control measures. Officials say this December is on track to be the dirtiest in eight years as air quality worsens across the region.

Temperatures continue to fall, with Friday's minimum at 9°C, slightly above normal. Forecasts suggest a further drop to 7-9°C on Saturday, with maximum temperatures expected to range between 21-23°C over the weekend and decline further by mid-next week. The Supreme Court has directed the Commission for Air Quality Management to move from short-term measures to comprehensive reforms.

The court emphasised the need for sustainable solutions addressing urban mobility, industrial emissions, and agricultural burning, urging coordinated action between Delhi, Uttar Pradesh, Haryana, and Rajasthan. The next hearing is scheduled for 6 January.

Meteorologists warn that falling temperatures could intensify the inversion effect, trapping pollutants near the ground. Anumita Roychowdhury, executive director at the Centre for Science and Environment, explained that a drop in temperature can cause pollutants to get trapped near the lower layers of the atmosphere. The severity of the spike will depend on meteorological factors like wind speed.

Vehicular pollution contributed 15.72 per cent to Friday's pollution levels, according to the Decision Support System for Air Quality Management. This is expected to rise to 17.36 per cent on Saturday and 18.41 per cent on Sunday, despite enforcement against older vehicles and those without valid pollution certificates.