Dense fog in Delhi as AQI worsens again; flights, rail operations impacted

The India Meteorological Department (IMD) said visibility dipped to 100 metres at both Safdarjung and Palam, between 5:30am and 6:30am

Dense fog engulfed the national Capital on Thursday morning, with both flight and rail operations impacted as air quality deteriorated in the city again. The average air quality Index (AQI) stood at 358 at 9am on Thursday - up from a reading of 334 on Wednesday at 4pm.

The fog impacted operations at Delhi’s Indira Gandhi international (IGI) airport, with over 150 flights delayed. (HT photo)

The India Meteorological Department (IMD) said visibility dipped to 100 metres at both Safdarjung and Palam, between 5:30am and 6:30am but is not expected to drop further.

“At 2:30am, visibility at Safdarjung was 300 metres and it was 500 metres at Palam. Visibility continued to dip and touched 100 metres at both stations, but should increase in the coming hours again,” said an IMD official.

To be sure, the IMD had forecast shallow to moderate fog in the capital for Thursday.

The fog impacted operations at Delhi’s Indira Gandhi international (IGI) airport, with over 150 flights delayed, data from flight tracking website Flightradar24 showed.

On Monday - the city’s first very dense fog day, over 800 flights were delayed, over 200 cancelled and five had to be diverted due to bad weather as visibility plummeted to zero at Safdarjung and was 50 metres at Palam.

The IMD classifies fog as shallow between 500-1000 metres, as ‘moderate’ when visibility is between 200-500 metres, as ‘dense’ when it is between 50 and 200 metres and as ‘very dense’ below 50 metres.

Directorate General of Civil Aviation (DGCA) norms allow aircraft to land with visibility as low as 50 metres, but require a minimum visibility of 125 metres for take-offs.

The Delhi airport posted on X on Thursday morning, warning disruptions are expected due to dense fog.

“Due to dense fog, flight operations are currently under CAT-3 conditions, which may lead to delays or disruptions. We are working closely with all stakeholders to minimise inconvenience to passengers,” said the post at 8:10am.

Northern Railways officials also said several trains were delayed.

On Thursday, strict vehicle restrictions will kick into place in the national Capital.

Vehicles not registered in Delhi that are lower than BS VI standards will not be allowed to enter the capital. Similarly, vehicles without a valid PUC certificate will be denied fuel at fuelling stations - as part of the Delhi government’s plans to curb air pollution.