Eleven flights bound for the Indira Gandhi International Airport in Delhi were diverted to other cities on Monday due to heavy smog and poor visibility caused by adverse weather conditions. The flights were diverted under the 'Captain Minima' operating procedures, which set the minimum standards for pilots when landing. If weather conditions don’t meet these standards, diversions are made to ensure safety.

Initially, eight flights were diverted to cities like Jaipur and Dehradun in the morning. By early afternoon, the number of diversions increased to eleven. The Delhi Airport issued an advisory to passengers informing them that flight operations could be affected due to low visibility. The advisory encouraged passengers to contact their airlines for updated information on their flights.

Meanwhile, the air quality in Delhi worsened significantly, reaching 'severe plus' levels. The Central Pollution Control Board (CPCB) recorded an Air Quality Index (AQI) of 490 at 1 PM. Areas like Dwarka Sector 8, Ashok Vihar, and Mundka reported AQI levels above 490, with some locations like RK Puram and Chandani Chowk also showing high pollution levels.

In response to the deteriorating air quality, the Commission for Air Quality Management (CAQM) implemented the Graded Response Action Plan (GRAP) Stage 4 in Delhi NCR. This decision followed a sharp rise in Delhi's daily average AQI, which reached 441 by 4 PM on Sunday, further increasing to 457 by 7 PM.

As part of the Stage 4 measures, trucks entering Delhi have been banned, except for those transporting essential goods or services. Only LNG, CNG, electric, and BS-VI diesel trucks will be allowed. Medium and heavy goods vehicles registered outside Delhi, as well as Delhi-registered BS-IV and older diesel vehicles, will not be allowed to operate, except for those carrying essential services.

Additionally, construction and demolition activities have been banned, extending to public infrastructure projects such as highways, roads, and power transmission lines. These actions are part of a wider effort to mitigate the city's pollution crisis.