India, Dec. 16 -- Delhi's air quality index (AQI) was in the severe range - above 400 -- for the third consecutive day on Monday. This followed a reading of 461 on Sunday, which is classified in the severe plus sub-category of the severe range. However, a countrywide analysis shows that Delhi is not alone in experiencing a deterioration in air quality currently. Since December 12, when a western disturbance started approaching northern India, several cities in the region have experienced a deterioration in air quality. Here's how this has played out:

Published by HT Digital Content Services with permission from Hindustan Times....