Every smog episode in Delhi is invariably blamed on crop stubble burning by farmers in the neighbouring states. Scientists agree that events like Diwali and stubble burning may be pushing pollution levels to “emergency” levels briefly, but that cannot take away from the fact that Delhi’s local emissions have only risen over the years. Central Pollution Control Board’s national air-quality monitoring programme (NAMP), which has been tracking annual PM2.5 and PM10 levels since 2009, shows a clear trend of rising PM2.5 levels over the years, picking pace in 2015, 2016 and 2017.

TOI accessed annual average PM10 and PM2.5 levels for Delhi for eight years. While PM10 levels have continuously been 3-5 times the annual safe…