Delhi residents woke up on Tuesday to heavy grey haze darkening the city skies, reduced visibility and the air quality in the 'red zone' after many celebrated Diwali last night by bursting firecrackers beyond the two-hour limit set by the Supreme Cour, reported news agency PTI.

According to a Central Pollution Control Bureau (CPCB) bulletin, Delhi's Air Quality Index (AQI) was 'very poor', with a reading of 352 at 8 am. It was 346 at 5 am, 347 at 6 am and 351 at 7 am, reported PTI.