The remaining two-thirds is contributed by other NCR cities such as Noida, Greater Noida, Gurgaon, Faridabad and Ghaziabad; and districts outside the NCR, such as those in Punjab and Haryana, where farmers set fire to fields to get rid of paddy stubble.

The air quality index for other NCR cities is in the ‘very poor’ category, with the weather office offering no hope for an immediate improvement.

The India Meteorological Department said dense to very dense fog will continue for the next few days and the temperature will further drop.

The GRAP for Delhi-NCR is divided into four air quality stages – stage 1 for ‘poor’ AQI between 201 and 300; stage 2 for “very poor” AQI of 301-400; stage 3 for “severe” AQI of 401-450 and stage 4 for “severe plus” AQI (greater than 450).