Delhi shrouded in smog after Diwali

Air quality had already deteriorated sharply ahead of the main celebration – as this picture of a cluster of temples in the Indian capital shows from a couple of days earlier. As winter approaches, air quality tends to worsen for various reasons, including the burning of crop residues outside the city and increased diesel emissions.

Diwali is traditionally celebrated by the lighting of lamps, but firecrackers have since become an integral part of the tradition. They’re also used in wedding ceremonies. Explosions often occur in the illegal backyard and underground workshops that make firecrackers for the event. An explosion at a licensed factory in the state of Uttar Pradesh last month killed seven people.

Here, one of Delhi's most popular landmarks, the Red Fort, appears in a haze on the day after the main Diwali celebrations. In October, India’s Supreme Court ruled that the use of Diwali fireworks should only take place within a narrow time window and that only "green" fireworks — which give off less soot and smoke — should be used. However, authorities appeared reluctant to enforce the rules.

The five-day festival of lights is principally seen as a Hindu celebration, symbolizing "the victory of light over darkness, good over evil and knowledge over ignorance." In the northern hemisphere, it falls between mid-November and coincides with the new moon, with the main day of celebration being the third day. Diwali is also a time of celebration for Sikhs, Jains, and some Buddhists.

Some, like this family on the morning after Diwali, choose to wear masks to protect themselves. But the practice is nowhere near as popular in Delhi as it is in other cities affected by smog, such as Beijing. Children are particularly vulnerable. Last month the World Health Organization said exposure to toxic air indoors and out kills some 600,000 children under the age of 15 each year.