In pictures: North India goes up in smoke

Last month, a Supreme Court order set rules last month regarding the lighting of firecrackers, saying "green crackers" with low emission levels were permitted, and could be burst only between 8 pm and 10 pm on festival days. The order was largely observed in the breach, leaving citizens choking on the lingering evidence.

It is well known that air pollution in North India peaks at dangerous levels around festival time. This year, the national capital was enveloped in a thick smog well before Diwali, which fell on Tuesday, November 7. This was largely due to the burning of crop stubble in parts of north India, a relatively recent phenomenon arising from the adoption of combine harvesting. Earlier, farmers would till plant remains back into the soil. But as harvesting combines became popular, so did burning, because machine-cut fields were left with stalks that were hard to get rid of quickly. Burning is seen as the cheapest and fastest way to clear a field and prepare it for the next crop. Despite efforts to curb it, crop burning seems to become more common every year. 

On Saturday, November 10, air quality in Delhi fell from 'very poor' to 'severe'. The images below tell the story of the run-up to Diwali and its aftermath.