As many as 34 Delhi-bound trains were delayed and eight cancelled on Sunday morning because of poor visibility as smog continued to envelop parts of North India. Air quality levels remain in the ‘severe’ category on Sunday, ANI reported. Twenty-one trains were rescheduled.

An Air Quality Index reading up to 50 is considered ‘good’, and up to 100 is considered ‘satisfactory’. A reading between 401-500 is ranked ‘severe’ on the index, which means the air is dangerously filled with pollutants.

The India Meteorological Department, however, has forecast rain on November 14 and 15, which may help clear the smog, the Hindustan Times reported.

The Central Pollution Control Board’s air quality index showed its maximum reading of 500 for Vasundhara, Ghaziabad, 495 for Punjabi Bagh and 493 for ITO area. Readings for all stations were above 460. Readings between 401 and 500 are classified as ‘severe’ air quality.

Other North Indian cities also showed 400-plus readings, with Agra at 420, Noida at 500, Gurugram at 461 and Rohtak at 459.

The concentration of particulate matter PM10 at noon was 706.7 micrograms per cubic metre in Delhi, according to the CPCB. The PM2.5 concentration was 470.3 micrograms per cubic metre.

At 11.54 am, the PM10 level at Delhi University rose to 614, while the PM2.5 level was 571, according to SAFAR. The PM10 levels at Lodhi Road were 560 and the PM2.5 level was 625. All were categorised as ‘severe’.