As of Wednesday, New Delhi’s PM 2.5 concentration – a measure of pollutants in the air – was more than 40 times the World Health Organization’s annualized guideline level, according to Swiss air quality monitoring company IQAir. New Delhi grapples with severe year-round pollution, but the winter months are typically worst, when millions of farmers in surrounding regions burn stubble in their fields to clear the way for the next crop.
The sharp deterioration in air quality this week comes following celebrations for Diwali, the Hindu festival of lights, which traditionally involves the widespread use of firecrackers which release sulfur oxides and nitrogen oxides into the air, as well as harmful heavy metals.
