This month, the Supreme Court relaxed a ban on fireworks during the festival of lights, allowing the use of less-polluting “green firecrackers” – designed
to emit fewer particulates.

The ban was widely ignored in past years, however, and environmental groups have expressed doubts about the efficacy of the supposedly greener explosives.

Early on Tuesday morning (local time), just after the peak of the bursting fireworks, levels of cancer-causing PM 2.5 microparticles hit 846 micrograms per cubic metre in parts of New Delhi, according to monitoring organisation IQAir.

That is more than 56 times the World Health Organisation’s recommended daily maximum.