Last week Delhi CM Arvind Kejriwal had said that pollution levels in Delhi, primarily the concentration of particulate matter, has reduced by 25% over a period of four years.
According to a global study five years ago, in 2014, World Health Organisation had declared Delhi the most polluted city in the world. Since then, the Centre, states and courts have taken several steps to improve air quality in the city.
It was in 2012 that Delhi saw its worst air quality, a senior official of the Delhi Pollution Control Committee (DPCC) said. “We felt the full force of crop-residue burning that year, especially in October and November. It was the first time that this burning was seriously flagged. We realised this was a big reason for the sudden dip in air quality in Delhi,” he said.
But since 2012, the average annual concentration of particulate matter — the primary cause of pollution in the city — has been falling.