Delhi has recorded the highest level of pollution post-Diwali this year followed by Chennai and Bangalore
The air quality in Delhi severely deteriorated a day after Diwali with the city recording nine times higher pollution level than the normal.
The Respirable Suspended Particulate Matter (RSPM), which directly affects breathing, was at 531 mg per cubic metre, more than five times higher than the normal level leaving many at risk of respiratory problems.
A warning was issued by Gufran Beig, chief scientist at the Indian Institute of Tropical Meteorology earlier this week based for the first time on India's newly launched national Air Quality Index. The warning was significant as New Delhi dismissed a World Health Organization study in May which found the capital to have the world's worst air pollution.
The study, which covered 1,600 cities, also said that India has 13 of the 20 cities with the worst air quality worldwide.
Pollution levels in Indian cities have often been compared to Chinese counterparts such as Beijing, notorious for the smog that prompted some Anglophone residents to dub it "Greyjing".
Delhi has recorded the highest level of pollution post-Diwali this year followed by Kolkata where the SPM level was 417 mg per cubic metre, and Chennai at 320 mg per cubic metre.