The dense fog returned to Delhi and surrounding areas like Ghaziabad and Noida on Friday morning, reducing visibility to zero in some locations and prompting the Indira Gandhi International Airport (IGI) to issue an advisory due to potential flight disruptions. This dense fog arrived alongside a worsening Air Quality Index (AQI) in Delhi-NCR. At 6:05 am on Friday, the overall AQI in Delhi was recorded at 409, falling into the ‘severe’ category, according to the Sameer app, which provides hourly AQI data.

The exact number of affected flights and trains was not immediately available on Friday morning, but reports indicated that over 100 flights were delayed at IGI Airport. Delhi’s temperature was recorded at 9.6 degrees Celsius at 5:30 am, with the India Meteorological Department (IMD) predicting a minimum temperature of around 6 degrees Celsius and a maximum of approximately 20 degrees Celsius, accompanied by “very dense fog.”

Flight Operations at IGI Airport Impacted

At 4:25 am, IGI Airport issued an advisory advising passengers to check with their respective airlines for updates on flight statuses due to the potential impact of dense fog on operations. In a subsequent advisory at 5:52 am, the airport confirmed delays in flight departures but noted that flights compliant with CAT III technology were still able to land and depart. “Due to dense fog, there has been an impact on flight departures, but CAT III-compliant flights can land and depart from Delhi Airport. Passengers are requested to contact their airlines for updated flight information,” the advisory stated.

At 5:04 am, IndiGo also posted a message on X (formerly Twitter) urging passengers to stay updated on their flight status before arriving at the airport.

Delhi and other NCR cities, including Noida, Ghaziabad, and Gurugram, experienced similar conditions between January 2 and 3, with visibility dropping to zero for an unprecedented nine-hour stretch, marking the longest fog spell of the season according to weather reports. On Thursday, Delhi experienced a sunny afternoon, with a maximum temperature of 21.2 degrees Celsius, 2.2 degrees higher than the season’s normal. However, the morning was colder, with a minimum temperature of 4.8 degrees Celsius, down from 7.4 degrees Celsius on Wednesday, accompanied by light fog.

GRAP Stage 3 Reimposed Amid Poor Air Quality

The Centre’s panel on Delhi-NCR’s air quality reintroduced stage 3 anti-pollution measures under the Graded Response Action Plan (GRAP) due to a significant rise in air pollution, exacerbated by unfavorable weather conditions. By 4 pm, the 24-hour average AQI had risen to 357, compared to 297 on Wednesday, due to “calm winds and foggy conditions.”

The Commission for Air Quality Management (CAQM), responsible for air pollution control in Delhi-NCR, ordered authorities to implement GRAP’s stage 3 measures immediately to prevent further deterioration. Under the AQI system, an AQI between 0-50 is ‘good,’ 51-100 is ‘satisfactory,’ 101-200 is ‘moderate,’ 201-300 is ‘poor,’ 301-400 is ‘very poor,’ and 401-500 is ‘severe.’

GRAP Stage 3, reintroduced on Sunday, includes a ban on non-essential construction activities. Additionally, an annual report by the Centre for Research on Energy and Clean Air (CREA) highlighted that Delhi recorded a 12% reduction in air pollution compared to its 2017 baseline, with PM10 levels decreasing from 241 to 211 µg/m³. Despite this progress, Delhi still did not meet its target. The report also revealed that only 41 of the 131 cities identified as part of the National Clean Air Programme (NCAP) managed to meet their 2024 goal of reducing PM10 levels by 20-30%.